A2.4 l balloon holds 3.7 mol he. if 1.6 mol he are added to the balloon, what is the new volume? -3.4 l -34 l -1.7 l -0.12 l

For this question, lets apply Avagadro's law
when Pressure and temperature are constant, the volume occupied is directly proportional to the number of moles of gases.

where V-volume, n-number of moles and k - constant 
Therefore at 2 instances 

where V1 and n1 are for 1st instance 
and V2 and n2 are for 2nd instance 
therefore 

V1 = 2.4 L
n1 = 3.7 mol
n2 = 3.7 + 1.6 = 5.3 mol
since more He moles are added at the 2nd instance its the sum of the moles.
V2 needs to be calculated 
V2 = 2.4 x 5.3 / 3.7
     = 3.4 L
Answer is 1st option 3.4 L

The answer is option B

Explanation:

The density of a substance can be found by using the formula

From the question

mass of mineral = 100 g

volume = 50 cm³

The density of the mineral is

We have the final answer as

2.0 g/cm³

Hope this helps you