If 10 volumes of H₂ react completely with 5 volumes of O₂, what volume of water vapor will be produced under the same conditions of temperature and pressure?

1. Nine (9)

2. Eight (8)

3. Ten (10)

4. Eleven (11)

Find the value of 15.15 pm expressed in the basic SI unit of length.

1. 1.515 × 10^–12 

2. 2.57 × 10^–11 m

3. 2.87 × 10^–11 m

4. 1.515 × 10^–11 m

Which will have the largest number of atoms among the following?

What would be the molarity of a solution of ethanol in water if the mole fraction of ethanol is 0.040?
(assume the density of water to be 1)
1. 3.143 M

2. 2.314 M

3. 2.413 M

4. 2.141 M

What is the mass, in grams, of one atom of carbon-12 (¹²C)?

1. 1.393 x 10^-23

2. 1.993 x 10^-23

3. 1.773 x 10^-23

4. 1.593 x 10^-23

Determine the number of significant figures that should be present in the final answers for each of the following expressions:

The molar mass of naturally occurring Argon isotopes is: 

Which of the following contains the highest number of atoms?

1. 52 moles of Ar

2. 52 u of He

3. 52 g of He

4. All of the above have the same number of atoms

Burning a small sample of welding gas (constituted of C and H only)  in oxygen gives 3.38 g carbon dioxide, 0.690 g of water, and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g. Molecular formula of welding gas would be:

1. C₂H₂

2. C₂H₆

3. CH

4. C₂H₄

Find the mass of CaCO₃ required to completely react with 25 mL of 0.75 M HCl according to the reaction:

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l)

1. 0.36 g

2. 0.09 g

3. 0.96 g

4. 0.66 g