UNIT 1: Basic Concepts of Chemistry and Chemical Calculations - Online Test
Q1. The
mass of a gas that occupies a volume of 612.5 ml at room temperature and
pressure (250 c and 1 atm pressure) is 1.1g. The molar mass of the
gas is
Answer : Option B
Explaination / Solution:
No. of moles of a gas that occupies a volume of
612.5 mL at room temperature and pressure (25 0 C and 1 atm
pressure)
=612.5 × 10-3 L / 24.5 Lmol-1
=0.025 moles
We know that,
Molar mass
=Mass / no. of moles
=1.1 g
/0.025 mol = 44 g mol-1
Q2. Which
of the following contain same number of carbon atoms as in 6 g of carbon-12.
Answer : Option C
Explaination / Solution:
No. of moles of carbon present in 6 g of C-12 =
Mass / Molar mass
=6/12 = 0.5 moles = 0.5 × 6.022 × 1023
carbon atoms. No. of moles in 8 g of methane = 8 / 16 = 0.5 moles
=0.5 × 6.022 × 1023 carbon atoms.
=2 × 0.25 × 6.022 × 1023 carbon atoms.
Q3. Which
of the following compound(s) has /have percentage of carbon same as that in
ethylene (C2H4)
Answer : Option A
Explaination / Solution:
Q4. Which
of the following is/are true with respect to carbon -12.
Answer : Option A
Explaination / Solution:
(a)
relative atomic mass of C-12 is 12 u
Q5. Which
one of the following is used as a standard for atomic mass.
Answer : Option A
Explaination / Solution:
No Explaination.
