on the basis of the reaction of heat in plastic , their are two types of plastics :
Thermoplastic & Thermosetting plasticsThermoplastics : Plastics which easily get deformed (become soft )on heating and also get bend easily are known as thermoplastics .
examples : polythene , polyvinyl chloride and polystyrene .
thermosetting plastics : plastics which once moulded into a shape do not become soft on heating and cannot be moulded again are called thermosetting plastics .
examples : bakelite , melamine and formica
all isotopes of uranium have how many protons
The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%)
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Copper has two naturally occurring isotopes, 63 Cu and 65 Cu. If that is the case, why is the atomic mass of the copper listed as 63.55 amu on the periodic table ????
Explanation: There are 2 given isotopes of Copper.
Mass number of Isotope 1 : 63amu
Mass number of Isotope 2: 65 amu
Let the fractional abundance of isotope 1 be 'x', so the fractional abundance for Isotope 2 will be '1-x'
The average atomic number of Copper given is 63.55 amu.
So, the formula for average atomic mass is given by:
[tex]\text{Average atomic mass of an element}=_{i=1}^n\sum{\text{atomic mass of isotopes}_i\times {\text {fractional abundance}_i}[/tex]
Putting values in above equation, we get:
[tex]63.55=[(63\times x)+(65\times (1-x))]\\\\x=0.725[/tex]
The fractional abundance of Isotope 1 = 0.725
The fractional abundance of Isotope 2 = 0.275
So, the natural percentage abundance for isotope 1 = 72.5%
The natural percentage abundance for isotope 2 = 27.5%
Whenever more number of isotopes are present of an element are present, we take the average atomic mass of that element.
Which answer choice provides the best set of tables for wave a and wave b
Answer:
Option D
Wave A: Low Frequency Wave
Wave B: High Frequency Wave
Help. The third and last question are
3 A 2- N force presses down on the marble at the same time as a 1.5N force acts on the right side of the marble
4 A marble rolling downhill suddenly comes to rest at a garden wall
Balanced forces means the forces acting on the object are either equal but in opposite directions or zero.
For the first option, something starting to roll means it has an unbalanced force acting on it.
For the second option, these forces are equal and in opposite directions, so these are balanced forces.
For the third option, the forces are not equal and not in opposite directions, so these are unbalanced forces.
And for the last option, something that changes speed does not have balanced forces.
The questions pertain to the effects of forces on an object (a marble) within the field of physics. The first involves combining two forces acting in different directions, and the second involves Newton's first law of motion.
Explanation:The subject of these questions pertains to force and its effects, specifically in the context of physics. In the first scenario, we're looking at the combination of two forces on an object (the marble). The 2-N force pressing down and 1.5-N force acting to the right will result in a net force at an angle, according to vector addition. In the second scenario, the concept of Newton's first law of motion comes into play. The marble, initially in motion, comes to rest when it hits the garden wall because an external force (the wall) is applied, disrupting its initial state of motion.
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If you drop a 25-gram piece of metal that has a temperature of 100° Celsius into 1000 grams of water at 20° Celsius, what best describes what would occur?
1. the temperature lost by the metal will equal the temperature gained by the water
2. the heat lost by the metal will equal the heat gained by the water
3. the final temperature will be 60 degrees celsius
4. the final temperature will be more than 60 degrees celsius
Answer is: 2. the heat lost by the metal will equal the heat gained by the water.
1) the temperature lost by the metal will equal the temperature gained by the water is not correct, because temperature is the intensity of heat present in a substance and a thermometer is a device that measures temperature or a temperature gradient.
3) the final temperature will be 60 degrees celsius is not correct, because amount of water is greater than amount of metal, so the the final temperature will be less than 60 degrees celsius.
4) same as 3).
What is the difference between atomic mass and atomic numbers
Atomic mass (amu) = the number of protons and electrons
Atomic numbers = the little number on the periodic table that any element has which represents the number of protons in the nucleus
Atomic number is the number of protons that are inside that atom. This helps identify which element an atom is.
Atomic mass is the number of protons and neutrons inside an atom.
Which of the following is a noncontact force?
A.
magnetic forces
B.
electrical forces
C.
gravitational forces
D.
all of these
which part of the periodic would contain an element with a partially filled f sublevel
Answer: Lanthanide and actinide series
Explanation: The elements with partially or fully filled f orbitals belong to f block elements.
f block elements include lanthanides and actinides. They are called so the lanthanides contain the first element named as lanthanum and actinides contain first element named as actinium. They are also called as inner transition elements.
All of them have general electronic configuration:
[tex](n-2)f^{1-14}(n-1)d^{0-10}ns^2[/tex], where n = 6-7
Answer: The very bottom row. Its like a light color orange.
Explanation: That's the f subleavel.
Which one is more dangerous Ac or Dc how is it?
Question
Which one is more dangerous Ac or Dc how is it?
Answer
AC
_________________
AC has the voltage alternates, it enter and exit from your body without a closed loop.
you have a big block of ice you chip off a small chunk which has more thermal energy?
A. the big block
B. the small chunk
C. they have the same amount of thermal energy
What mass of acetylene gas, C2H2, would be produced by complete reaction of 3.75g of calcium carbide
The mass of C2H2 produced by the reaction of 3.75g of CaC2 can be calculated using the balanced chemical equation and the molar masses of CaC2 and C2H2. The number of moles of CaC2 and C2H2 can be determined, and then multiplied by their respective molar masses to find the mass of C2H2 produced.
Explanation:To answer the question, we need to use the balanced chemical equation for the reaction between calcium carbide (CaC2) and water (H2O):
CaC2 (s) + 2H2O (l) → C2H2 (g) + Ca(OH)2 (s)
From the equation, we can see that 1 mole of calcium carbide reacts to produce 1 mole of acetylene gas.
Now, we need to calculate the number of moles of calcium carbide using its molar mass:
Molar mass of CaC2 = 40.08 g/mol + 12.01 g/mol × 2 = 64.10 g/mol
Mass of CaC2 = 3.75
Number of moles of CaC2 = Mass of CaC2 / Molar mass of CaC2 = 3.75 g / 64.10 g/mol = 0.0585 mol
Since 1 mole of CaC2 produces 1 mole of C2H2, the number of moles of C2H2 produced is also 0.0585 mol.
Finally, we can calculate the mass of C2H2 produced using its molar mass:
Molar mass of C2H2 = 12.01 g/mol × 2 + 1.01 g/mol × 2 = 26.04 g/mol
Mass of C2H2 = Number of moles of C2H2 × Molar mass of C2H2 = 0.0585 mol × 26.04 g/mol = 1.52 g
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One effect of the increase of greenhouse gases causing global warming is _______________.
Question 6 options:
drought
more food supply
increase in fossil fuels
Answer:
drought
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Which of the following choices demonstrates how the writer creates the point that physical responses to stressful situations is part of human nature? A) The author compares a caveman physically responding to a tiger to a modern man physically responding to an unknown situation at work. B) The author examines the stressful situation people face today and concludes that they are much more stressful than those faced in the past. C) The author stresses that physical reactions to stress are always positive. D) The author explains that cavemen used their physical responses to survive.
D I believe is the correct answer
What is the oxidation number of Mn in Ca(MnO4)2
Answer:
+ 7.
Explanation:
We have general rules to assign the oxidation numbers:
Rule 1: The oxidation number of an element alone in its free (uncombined) state is zero.
For example, Al(s) or Zn(s).
This is also true for elements found in nature as diatomic (two-atom) elements as: H₂, O₂, Cl₂, or I₂.
and also for sulfur, found as: S₈.
Rule 2: The oxidation number of a monatomic (one-atom) ion is the same as the charge on the ion,
For example: Na⁺ = +1, S⁻² = -2.
Rule 3: The sum of all oxidation numbers in a neutral compound is zero. The sum of all oxidation numbers in a polyatomic (many-atom) ion is equal to the charge on the ion.
Rule 4: The oxidation number of an alkali metal (group IA) in a compound is +1; the oxidation number of an alkaline earth metal (group IIA) in a compound is +2.
Rule 5: The oxidation number of oxygen in a compound is usually –2.
If, however, the oxygen is in a class of compounds called peroxides.
(for example, hydrogen peroxide), then the oxygen has an oxidation number of –1. If the oxygen is bonded to fluorine, the number is +1.
So, for our problem Ca(MnO₄)₂:
The sum of all oxidation numbers in a neutral compound is zero.The oxidation no. of Ca which is in (group IIA) = +2.The oxidation no. of O = -2.∴ oxidation no. of Ca + 2[(oxidation no. of Mn) + 4(oxidation no. of O) = 0.
(+2) + 2[(oxidation no. of Mn) + (- 8)] = 0.
2[(oxidation no. of Mn) + (- 8)] = - 2.
[(oxidation no. of Mn) + (- 8)] = -1.
∴ (oxidation no. of Mn) = - 1 + 8 = + 7.
+7 is the oxidation number of manganese atom (Mn) in Ca(MnO₄)₂.
What does oxidation number tells about?Oxidation number of any substance will tell about the import and export number of electrons from that substance.
Given compound is Ca(MnO₄)₂, this is a neutral compound means no charge is present on the compound. Oxidation number of Calcium (Ca) is +2, oxidation number of oxygen atom (O) is -2 and let the oxidation number of manganese (Mn) be x.
Total sum of the oxidation number of all atoms equals to the whole charge of the compound and calculation for oxidation number will be calculated as:
+2 + 2[x + 4(-2)] = 0
2 + 2x - 16 = 0
2x = 16 - 2
2x = 14
x = 7
Hence, +7 is the oxidation number.
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State the general relationship between temperature of the water and the amount of the salt that will dissolve in the water
Generally for simpler salts like sodium chloride, when the salts gets dissolved in water the temperature slightly decreases. But for salts which comes in the form of pellets which are more exothermic increases the temperature of water. The increase or decrease in the temperature depends upon the type of salt that is dissolved in the water.
Which of the following statements is true for an exothermic reaction?
The products have higher potential energy than the reactants, and the enthalpy change is negative.
The products have higher potential energy than the reactants, and the enthalpy change is positive.
The products have lower potential energy than the reactants, and the enthalpy change is negative.
The products have lower potential energy than the reactants, and the enthalpy change is positive.
What does a process require to be spontaneous at all temperatures? (2 points)
a catalyst and lower activation energy
a heat source and high activation energy
positive enthalpy and negative entropy changes
negative enthalpy and positive entropy changes
Final answer:
In an exothermic reaction, the products have lower potential energy than the reactants, and the enthalpy change is negative. A process requires a negative enthalpy change and a positive entropy change to be spontaneous at all temperatures.
Explanation:
For an exothermic reaction, the correct statement is: The products have lower potential energy than the reactants, and the enthalpy change is negative. This is because an exothermic process involves the release of energy, typically in the form of heat, as the reactants transform into products. The products are more stable and lower in energy compared to the reactants, and the enthalpy change (ΔH) is negative, indicating that energy has been released to the surroundings.
For a process to be spontaneous at all temperatures, it must have a negative enthalpy change and a positive entropy change. This combination of factors means that the process is both energetically favorable and leads to an increase in the disorder or randomness of the system.
Which of the following colors of visible light has the lowest energy?
A) blue
B) green
C) red
D) yellow
Answer:
Its blue
Explanation:
What is magma? a. The molten mixture of rock-forming substances, gases, and water from the mantle.. c. Hardened lava on the surface of the Earth. b. Liquid rock that reaches the surface. d. All of the above Please select the best answer from the choices provided
Answer: A The molten mixture of rock-forming substances, gases, and water from the mantle..
Explanation:
A ballon is filled with 35 L of air at 2.0 atm. If the pressure is increase to 3.5 atm, what is the new volume?
Answer:
20 L
Step-by-step explanation:
Since temperature is constant, we can use Boyle’s Law.
p₁V₁ = p₂V₂ Divide each side by p₂
V₂ = V₁ × p₁/p₂
=====
Data:
p₁ = 2.0 atm; V₁ = 35 L
p₂ = 3.5 atm; V₂ = ?
=====
Calculations:
V₂ = 35 × 2.0/3.5
V₂ = 20 L
What is the symbol for an isotope of carbon with 7 neutrons?
C-13. 6 protons 7
neutrons.
Which equation is NOT balanced? a. 2H2 + O2 → 2H2O c. Fe2O3 + 3H2 → 2Fe + 3H2O b. 4NH3 + 5O2 → 4NO + 6H2O d. 3H2 + 2O2 → 2H3O
option d
the values are wrong on the right hand side of the equation, the right equation is above a,b,c.
The chemical equation that is NOT balanced is option d, which has an unequal number of atoms on the reactant and product sides.
To determine if a chemical equation is balanced, we must check that the number of atoms of each element on the reactant side is equal to the number of atoms of the same element on the product side. Comparing the given equations:
a. 2H₂ + O₂ → 2H₂O: This equation is balanced because there are 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation.c. Fe₂O₃ + 3H₂ → 2Fe + 3H₂O: This equation is also balanced, with 2 iron atoms, 3 oxygen atoms, and 6 hydrogen atoms on each side.b. 4NH₃ + 5O₂ → 4NO + 6H₂O: This equation is balanced when we count the nitrogen, oxygen, and hydrogen atoms.d. 3H₂ + 2O₂ → 2H₃O: This equation is NOT balanced because there are 6 hydrogen atoms on the reactant side but 6 hydrogen atoms and an extra oxygen atom on the product side.Thus, option d is the equation that is not balanced.
what is tihe minimum temperature needed to dissolve 130 grams of KNO3 in 100 grams of water
The minimum temperature needed to dissolve 130 grams of [tex]KNO_{3}[/tex] in 100 grams of water is the solubility of [tex]KNO_{3}[/tex] at that particular temperature.
Solubility is the maximum amount of solute that can dissolve in a solvent at a given temperature. A [tex]KNO_{3}[/tex] solubility chart or data table must be used to estimate the minimum temperature needed to dissolve 130gm of [tex]KNO_{3}[/tex] in 100gm of water.
Given:
Mass of [tex]KNO_{3}[/tex] = 130 gm,
Mass of water = 100 gm.
Let's assume that the solubility of [tex]KNO_{3}[/tex] in 100gm of water is 80gm at 20°C. The solubility limit will be exceeded (130gm > 80gm) if we attempt to dissolve 130gm of [tex]KNO_{3}[/tex] in 100gm of water at 20°C, producing an unsaturated solution. To find the minimum temperature needed for complete dissolution, we need to find the temperature at which the solubility of [tex]KNO_{3}[/tex] is equal to or greater than 130gm. If we refer to the solubility chart and find that at 30°C, the solubility of [tex]KNO_{3}[/tex] is 130gm in 100gm of water, then the minimum temperature required is 30°C.
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the reason why iodine sublimes
The intermolecular forces for Iodine are much lower than the energy needed to free it from its crystal lattice. Once Iodine has enough energy to break out of the lattice, it also has enough energy to separate from its neighbors. And so, it sublimes.
Which rule is used when writing the name of an ionic bass
Answer:
Name = name of metal + hydroxide.
Step-by-step explanation:
You name an ionic base according to the rule:
Name = name of metal + hydroxide
Thus,
NaOH = sodium hydroxide
Ca(OH)₂ = calcium hydroxide
Al(OH)₃ = aluminium hydroxide
2. What is the molarity of 100 mL of a 3.0% H2O2 (mass/volume) solution? What is the molarity of 100 mL of a 2.25% H2O2 solution?
The 3% mass/volume H₂O₂ means 3 g of H₂O₂ in 100 ml of water.
Now, Molarity (M) = No. of moles of H₂O₂ / Volume of solution in liter
No. of moles of H₂O₂ = Mass / Molar mass = 3 g / 34 g/mol = 0.088 mol
So, molarity = 0.088 × 1000 ml / 100 ml = 0.88 M
In case of 2.25 % H₂O₂,
No of moles = 2.25 g / 34 g/mol = 0.066 mol
Molarity = 0.066 mol / 0.100 L = 0.66 M.
The molarity of a 3.0% H₂O₂ solution is 0.88 M, and the molarity of a 2.25% H₂O₂ solution can be calculated using the same steps. The molarity of a solution is determined by dividing the moles of solute by the volume of the solution in liters.
Explanation:The molarity of a solution is represented by the formula:
Molarity (M) = (moles of solute) / (volume of solution in liters)
First, we need to calculate the moles of H₂O₂ in each solution:
For the 3.0% H₂O₂ solution:
Convert the mass of H₂O₂ to grams: 3.0% of 100 mL is 3 grams.Convert grams of H₂O₂ to moles: we need to use the molar mass of H₂O₂, which is 34.0147 g/mol. Therefore, 3 grams / 34.0147 g/mol = 0.088 moles.For the 2.25% H₂O₂ solution:
Follow the same steps as above, using the mass of the solution (2.25% of 100 mL is 2.25 grams) and the molar mass of H₂O₂.Now we can calculate the molarity of each solution:
For the 3.0% H₂O₂ solution: Molarity = 0.088 moles / 0.1 L = 0.88 M.
For the 2.25% H₂O₂ solution: Molarity = (moles of solute) / (volume of solution in liters).
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What element has the greatest number of valence electrons available for bonding? Selenium.
Boron.
Calcium.
Chlorine.
The greatest number of valence electrons available for bondinging is Chlorine.
Chlorine has the greatest number of valence electrons available for bonding among the options provided, with seven valence electrons as it is a halogen from Group 7A.
Explanation:The element with the greatest number of valence electrons available for bonding among the options given is Chlorine. Chlorine belongs to Group 7A of the periodic table, which contains the halogens. All halogens, including chlorine, have seven valence electrons and thus can form bonds by accepting an electron to achieve a full octet. Comparatively, Selenium, although it can expand its octet, typically has six valence electrons, while Boron has three, and Calcium has two in their outermost energy level.
Specifically certain Group 7A elements are known to exist in nature as diatomic molecules, such as F2, Cl2, Br2 and I2, indicating their strong tendency to bond with themselves or other elements. Moreover, fluorine, also a halogen, is known to have the highest electronegativity, implying a strong attraction for electrons to form bonds. This same logic applies to chlorine as well, though it is slightly less electronegative than fluorine. Thus, out of the options listed, chlorine is the element that has the most valence electrons ready to partake in bonding.
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Which of the following methods estimates geologic events by comparing the objects to the layer of Earth they were discovered in? Fossil dating Geologic dating Radioactive dating Relative dating
The answer is; Relative dating
This type of dating is not concerned with determining the absolute age of rock. It compares between rock layer and determines which is younger or older in comparison. Therefore relative dating is significant in arranging geologic events based on the stratigraphy of rock layers.
Answer: Relative dating
Explanation:
Relative dating is a technique of identifying the age of the material whether fossil or rocks by comparing them with the surrounding materials. This method takes into consideration the order of the geological events took place on earth. This can be done by stratigraphy. In stratigraphy the layers of the rocks and sediments are compared to determine the age of the object (fossil, rock). This method does not help in determining the exact or absolute age of the object.
Using the law of conservation of energy, explain why an LED light is more energy efficient that an incandescent light bulb.
Answer:
An LED light uses one-third the energy of an incandescent bulb to produce the same amount of light.
Step-by-step explanation:
A typical 100 W incandescent bulb produces about 5 % visible light, 83 % IR radiation, and 12 % heat (it is the IR radiation that makes the bulb feel hot).
It produces about 5 J of light energy for every 100 J of energy input.
A typical LED bulb produces about 15 % visible light and 85 % heat (LEDs feel cool, because they don't produce IR radiation).
It produces about 15 J of light energy for every 100 J of energy input.
Thus, an LED light is about three times as efficient at converting electrical energy into light
Final answer:
An LED light is more energy efficient than an incandescent bulb as it converts more electrical energy into light with less waste as heat, making it a cost-effective and environmentally friendly option.
Explanation:
Using the law of conservation of energy, an LED light is more energy efficient than an incandescent light bulb because it converts a higher percentage of electrical energy into light, with minimal energy wasted as heat. Incandescent bulbs, in contrast, waste much of their energy as heat. For example, a 60-W incandescent bulb can be replaced by a 15-W CFL (Compact Fluorescent Light), which has the same brightness and color, demonstrating CFL's higher efficiency. LED lights push this efficiency even further, being twice as efficient as CFLs and lasting five times longer, though initially more costly. The movement towards LED lighting is driven by their ability to reduce power consumption significantly, thus lowering the cost and environmental impact of lighting homes and businesses.
why is the fact that light travels at 300,000 km/s is a consequence of energy conservation?
Light traveling at a constant speed is a consequence of the conservation of energy and is embodied in Einstein's equation E = mc^2. This speed limit contributes to the principles of energy and mass-energy conservation, with implications for relativistic phenomena like time dilation and length contraction.
Explanation:The fact that light travels at 300,000 km/s is a consequence of the conservation of energy. This principle is embodied in Einstein's famous equation E = mc2, where E denotes energy, m denotes mass, and c denotes the speed of light. This equation suggests that mass and energy are interchangeable.
According to the theory of relativity, if an object with mass attempted to reach the speed of light, it would require infinite energy, which is physically impossible. Therefore, the speed of light is a universal speed limit. This limit contributes to the principle of energy conservation and the closely related concept of mass-energy conservation.
Further consequences of the speed of light include time dilation, length contraction, and increased momentum as objects approach this speed. Equivalently, if a mass could reach the speed of light, these effects suggest that it would convert into pure energy, again consistent with E = mc2 and the conservation of mass-energy.
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Compare photons and electrons. Which of the following statements is true?
Photon is a packet of light energy. Both photon and electron contribute mostly to the quantum mechanics of the atom. Every particle in quantum mechanical model is explained as dual natured, that is has both particle and wave nature. Photons exhibit wave light properties like diffraction, interference, etc.,At the same time they exhibit particle properties like having a definite momentum and position. Similarly electrons and other microscopic particles exhibit both particle and wave nature.
Therefore, the correct answer is:
Both photons and electrons display particle and wave-like behaviour.