Ahelium balloon is filled on the ground where the atmospheric pressure is 768 torr. the volume of the balloon is 8.00 m3. when the balloon reaches an altitude of 4200 m, its volume is found to be 16.8 m3. assuming that the temperature remains constant, what is the air pressure at 4200 m in torr? a. 1.61 x 103 b. 366 c. 543 d. 111 e. 89

The correct option is: B. 366 torr

Explanation:

Given: On the ground- Initial Volume: V₁ = 8.00 m³, Initial Atmospheric Pressure: P₁= 768 torr;

At 4200 m height- Final Volume: V₂ = 16.80 m³, Final Atmospheric Pressure: P₂ = ?

Amount of gas: n, and Temperature: T = constant

According to the Boyle's Law, for a given amount of gas at constant temperature:         P₁ V₁ = P₂ V₂

⇒  P₂ = P₁ V₁ ÷ V₂

⇒  P₂ = [(768 torr) × (8.00 m³)] ÷ (16.80 m³)

⇒  P₂ = 365.71 torr ≈ 366 torr

Therefore, the final air pressure at 4200 m height: P₂ = 366 torr.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g