which of the following is not a gas at room temperature and pressure? D) NH3 B)

Question

which of the following is not a gas at room temperature and pressure? D) NH3 B) CH4 A) 12 2) Which of the following is the definition of pressure? gravity x density x temperature E) height volume. 3) flask containing neon gas is connected to an open-ended mercury manometer. The open end where the prevailing pressure is 745 torr. The mercury is exposed to the atmosphere, connected to the flask level in the open arm is 5.0 below that in the arm of is the neon pressure, in torr? E) 745 torr D) 795 torr C) 50. torr B) -50, torr A) 695 tom 4) A sample of nitrogen gas at 298 k and 745 torr has a volume of L. volume will it occupy if the pressure is increased to 894 constant temperature? D) 112 L E)31.2 L A) 44.9 L B) 380 L 5) What is the molar mass of an unknown gas if a sample weighing 0.389 g is collected in a flask with a volume of 102 cm3 at 97 c and at a pressure of728 mmHg? (R 0.08206 L atm/K mol, 1 atm 760 mmHg). A) 8.28 x 10-3 g/mol B) 112 g/mol D) 187 g/mol E) 121 g/mol 6 Ammonia's unusually high melting point is the result of A) dipole-dipole forces. B) ionic bonding. C) hydrogen bonding. D) covalent bonding. E) London dispersion forces. given temperature is listed first. A) C7H16, C5H12 B) Xe, Kr

Explanation / Answer

1. Answer is (A) I2

I2 is solid at room temperature.

2. Answer is (C)

Pressure is defined as force per unit area.

4. Answer is (E)

We know that, at a constant temperature, P (pressure) and V (volume) are inversely proportional.

So,

P2V2 = P1V1

V2 = P1V1 / P2

     = (745 torr) (37.42 L) / (894 torr)

    = 31.2 L

5. Answer is (E)

PV = nRT

PV = (m/M)RT

Where,

P = Pressure = 728 mmHg = (728/760) atm = 0.96 atm

V = Volume = 102 cm3 = 102 mL =0.102 L

m = mass = 0.389 g

M = Molar mass = ?

R = 0.08206 L atm K-1 mol-1

T = 97 oC = (273 + 97) K = 370 K

Now, substituting these values we get

PV = (m/M)RT

(0.96 atm) (0.102 L) = (0.389 g / M) (0.08206 L atm K-1 mol-1) (370 K)

M = (0.389 g) (0.08206 L atm K-1 mol-1) (370 K) / [(0.96 atm) (0.102 L)]

M = 121 g mol-1

6. Answer is (C) hydrogen bonding

Ammonia (NH3) has electronegative nitrogen and hydrogen. Ammonia can form hydrogen bonds, which help to keep the individual molecules closer together.

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