Which of the following best describes how chemical changes differ from physical changes?A. Physical changes produce no new substances and chemical changes do.
B. Physical changes always involve the formation of a gas while chemical changes may not.
C. Physical changes can occur inside or outside the substance; chemical changes always occur outside.
D. Physical changes involve a change of state; chemical changes involve a change of shape.

Answer:   B. observed wavelength of light

Explanation:  The relation of Planck's constant relating the Joules of energy absorbed/released by matter is usually used to determine the energy of the photon. The mathematical expression is -

                            E= h c /

Thus as we can observe that the energy is directly proportional to the speed of light and inversely proportional to the wavelength of the light.

Thus , we can say that Planck's constant relates the Joules of energy absorbed/released by matter to the observed wavelength of light.

Answer: Option (C) is the correct answer.

Explanation:

When two nuclei and a subatomic particle like proton, neutron or high energy electron collide with each other then it results in the formation of two or more different nuclides.

For example,

Whereas in an electrochemical, thermochemical and chemical reaction there occurs change in number of electrons and not in number of protons or neutrons.

Thus, we can conclude that a change in the number of protons or neutrons occurs in nuclear reaction type of reaction.

A change in the number of protons or neutrons occurs inwhich type of reaction? A change in the number of protons or neutrons occurs innuclear reaction. The answer is letter C. The rest of the choices do not answerthe question above.

Chemical formula of iron (III) sulfide is Fe₂S₃.

What is chemical formula?

A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus and minus signs.

We can write a chemical formula by following steps-

1. Write both the atoms that are present in the chemical compound.

2. Write the valencies of both the atoms that are present in the chemical compound.

3. Now cross multiply both the atoms such that 1 atom's valency goes to the subscript of another atom and vice versa.

Given,

oxidation state of Fe = +3

Valency of Fe = 3

Valency of sulphide ion = 2

When we cross multiply both the atom's valencies we get chemical formula of iron (III) sulfide as Fe₂S₃.

Therefore, chemical formula of iron (III) sulfide is Fe₂S₃.

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this is a dilution equation where 50.0 mL of 1.50 M H₂SO₄ is taken and added to 200 mL of water.

c1v1 = c2v2

where c1 is concentration and v1 is volume of the concentrated solution

and c2 is concentration and v2 is volume of the diluted solution to be prepared

50.0 mL of 1.50 M H₂SO₄ is added to 200 mL of water so the final solution volume is - 200 + 50.0 = 250 mL

substituting these values in the formula

1.50 M x 50.0 mL = C x 250 mL

C = 0.300 M

concentration of the final solution is A) 0.300 M

Answer: 0.300M

Explanation:

1) Data:

a) Initial solution

M = 1.50M

V = 50.0 ml = 0.050 l

b) Solvent added = 200 ml = 0.200 l

2) Formula:

Molarity: M = moles of solute / volume of solution is liters

3) Solution:

a) initial solution:

Clearing moles from the molarity formula: moles = M × V

moles of H₂SO₄ = M × V = 1.5M × 0.050 l = 0.075 mol

b) final solution:

i) Volumen of solution = 0.050 l + 0.200l = 0.250l

ii) M = 0.075 mol / 0.250 l = 0.300M ← answeer