### NEET Chemistry - New - Some Basic Concepts of Chemistry

#### Question - 1

Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2 weighs 10 g and 0.05 mole of X3Y2 weighs 9 g, the atomic weights of X and Y are:

• A 40, 30
• B 60, 40
• C 20, 30
• D 30, 20

#### Question - 2

An element, X has the following isotopic composition 200X : 90%, 199X: 8.0%, 202X: 2.0%. The weighted average atomic mass of the naturally occurring element X is closest to :

• A 201 amu
• B 202 amu
• C 199 amu
• D 200 amu

#### Question - 3

Specific volume of cylindrical virus particle is 6.02 x 10-2 cc/g, whose radius and length are 7 Å and 10 Å respectively. If NA = 6.023 X 1023, find molecular weight of virus:

• A 15.4 kg/mol
• B 1.54 x 104 kg/mol
• C 3.08 x 104 kg/mol
• D 3.08 x 103 kg/mol

#### Question - 4

The number of significant figures for the three numbers 161 cm, 0.161 cm, 0.0161 cm are:

• A 3, 4 and 5 respectively
• B 3, 4 and 4 respectively
• C 3, 3 and 4 respectively
• D 3, 3, and 3 respectively

#### Question - 5

In the final answer of the expression  $\frac { (29.2-20.2)\quad (1.79\times { 10 }^{ 5 }) }{ 1.37 }$  The number of significant figures is :

• A 1
• B 2
• C 3
• D 4

#### Question - 6

Boron has two stable isotopes, 10B (19%) and 11B (81%). Calculate average atomic weight of boron in the periodic table:

• A 10.8
• B 10.2
• C 11.2
• D 10.0

#### Question - 7

In which case is the number of molecules of water maximum?

• A 18 mL of water
• B 0.18 g of water
• C 0.00224 L of water vapours at 1 atm and 273 K
• D 10-3 mol of water

#### Question - 8

The number of water molecules is maximum in:

• A 1.8 gram of water
• B 18 gram of water
• C 18 moles of water
• D 18 molecules of water

#### Question - 9

The number of atoms in 0.1 mole of a triatomic gas is (NA= 6.023 X 1023mol-1) :

• A 6.026 x 1022
• B 1.806 x 1023
• C 3.600 x 1023
• D 1.800 x 1022

#### Question - 10

Volume occupied by one molecule of water (density = 1 g cm-3) is :

• A 9.0 x 10-23cm3
• B 6.023 x 10-23cm3
• C 3.0 x 10-23cm3
• D 5.5 x 10-23cm3