The correct answer is 12.044 × 10²³ molecules.
The molecular mass of H₂S is 34 gram per mole.
Number of moles is determined by using the formula,
Number of moles = mass/molecular mass
Given mass is 68 grams, so no of moles will be,
68/34 = 2 moles
1 mole comprises 6.022 × 10²³ molecules, therefore, 2 moles will comprise = 6.022 × 10²³ × 2
= 12.044 × 10²³ molecules.
Answer: 1.67 kg
Explanation:
The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

Q = Heat absorbed=
=
(1kJ=1000J)
m= mass of substance = ?
c = specific heat capacity = 
Change in temperature ,
Putting in the values, we get:

(1kg=1000g)
Thus the mass (in kg) of the copper sample is 1.67
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Answer:
c.- How much of the reactants are needed and how much product will made.
Explanation:
The moles is the matter unit used in chemistry to simplify some calculations, instead of using grams. Also the moles are very useful because the chemical reaction can be balanced.
When a Chemical reaction is balanced, then it can be easily to calculate how many moles are necessary to add in a process to obtain a quantity of grams of a product.