The question is incomplete, here is a complete question.
An arctic weather balloon is filled with 27.8 L of helium gas inside a prep shed. The temperature inside the shed is 13 ⁰C. The balloon is then taken outside, where the temperature is -9 ⁰C. Calculate the new volume of the balloon. You may assume the pressure on the balloon stays constant at exactly 1 atm. Be sure your answer has the correct number of significant digits.
Answer : The new volume of the balloon is 25.7 L
Explanation :
Charles's Law : It is defined as the volume of the gas is directly proportional to the temperature of the gas at constant pressure and number of moles.

or,

where,
= initial volume of gas = 27.8 L
= final volume of gas = ?
= initial temperature of gas = 
= final temperature of gas = 
Now put all the given values in the above equation, we get:


Therefore, the new volume of the balloon is 25.7 L
The correct answer among the choices given above is the last option. When an acid reacts with an active metal, hydrogen gas is produced. The hydrogen in acid is displaced by the metal yielding hydrogen gas.
Mg + 2HCl = MgCl2 + H2
"cg" is centigram, which is one-hundredth of a gram.
I will first convert from g to cg (multiply by 100), then from mL to L (multiply by 1000).

According to law of conservation of mass.
In a chemical reaction Mass is neither created nor destroyed.
- Mass of product =Mass of reactant
#1
Mass of water

#2
Mass of sulphur:-
