Answer:
The law of conservation of mass states that in a closed system, mass is neither created nor destroyed during a chemical or physical reaction. The law of conservation of mass is applied whenever you balance a chemical equation.
Explanation:
According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such the amount of gas consumed or produced during a reaction.
It is applicable in a chemical when the the mass of the products in a chemical reaction is equal to the mass of the reactants.
But it is not applicable in a nuclear fusion as some of the mass is generated as energy.
Answer:
i would say the anwser is C
Answer: The volume of 0.684 mol of carbon dioxide at s.t.p. is 15.3 L
Explanation:
According to ideal gas equation:

P = pressure of gas = 1 atm (at STP)
V = Volume of gas = ?
n = number of moles = 0.684
R = gas constant = 
T =temperature =
(at STP)



Thus the volume of 0.684 mol of carbon dioxide at s.t.p. is 15.3 L
There are 4 electron pairs (3 bonding and 1 lone pair) so the angle is 107 degrees. The 4 electron pairs are repelled to give a tetrahedral arrangement but the molecule has a pyrimidal shape due to the lone pair.