Some Basic Concepts of Chemistry

Some Basic Concepts of Chemistry


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 X3Y 2 weighs 9 g, the atomic weights of X and
are

(a)40, 30
(b)60, 40
(c)20, 30
(d)30, 20


2.What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO3 is m mixed with 50 mL of 5.8% NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)

(a)  3.5 g   (b) 7 g
(c)  14 g   (d) 28 g


3.If Avogadro number NA, is changed from 6.022 × 1023 mol–1 to 6.022 × 1020 mol–1, this would change the mass of one mole of carbon the ratio of chemical species to each other in a balanced equation the ratio of elements to each other in a compound the definition of mass in units of grams. (2015)

4)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.
(2015)


5)A mixture of gases contains H2 and O2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two gases in the mixture?

16 : 1 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1 (2015, Cancelled)

6)Equal masses of H2, O2 and methane have been taken in a container of volume V at temperature 27 °C in identical conditions. The ratio of the volumes of gases H2 : O2 : methane would be


(a)
8 : 16 : 1
(b)
16 : 8 : 1

(c)
16 : 1 : 2
(d)
8 : 1 : 2 (2014)


7) When 22.4 litres of H2(g) is mixed with 11.2 litres of Cl2(g), each at S.T.P, the moles of HCl(g)
formed is equal to
(a)
1 mol of HCl(g)
(b)
2 mol of HCl(g)

(c)
0.5 mol of HCl(g)
(d)
1.5 mol of HCl(g).

(2014)


8) 1.0 g of magnesium is burnt with 0.56 g O2 in

a closed vessel. Which reactant is left in excess and how much? (At. wt. Mg = 24, O = 16)
(a)
Mg, 0.16
g
(b)
O2, 0.16 g

(c)
Mg, 0.44
g
(d)
O2, 0.28 g

(2014)

9)6.02 × 1020 molecules of urea are present in 100 mL of its solution. The concentration of solution is

(a)
0.001 M
(b)
0.1 M

(c)
0.02 M
(d)
0.01 M


(NEET 2013)

10. In an experiment it showed that 10 mL of 0.05 M solution of chloride required 10 mL of 0.1 M solution of AgNO3, which of the following will be the formula of the chloride (X stands for the symbol of the element other than chlorine)

X2Cl2     (b) XCl2    (c)  XCl4    (d) X2Cl (Karnataka NEET 2013)

11.Which has the maximum number of molecules among the following?
(a)
44 g CO2
(b)
48 g O3

(c)
8 g H2
(d)
64 g SO2

(Mains 2011)

12. The number of atoms in 0.1 mol of a triatomic
gas is (NA = 6.02 × 1023 mol–1)

(a)
6.026 × 1022
(b)
1.806 × 1023

(c)
3.600 × 1023
(d)
1.800 × 1022

(2010)





2

13. 25.3 g of sodium carbonate, Na2CO3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion,

Na+ and carbonate ions, CO32– are respectively (Molar mass of Na2CO3 = 106 g mol–1)
0.955 M and 1.910 M

1.910 M and 0.955 M

1.90 M and 1.910 M

(d)  0.477 M and 0.477 M
(2010)


14. 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be

(a)
3 mol
(b)
4 mol


(c)
1 mol
(d)
2 mol
(2009)

15. What volume of oxygen gas (O2) measured at 0°C and 1 atm, is needed to burn completely

L of propane gas (C3H8) measured under the same conditions?

(a) 5 L (b) 10 L (c)  7 L (d) 6 L

(2008)

16. How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g HCl?

0.011   (b) 0.029  (c)  0.044  (d) 0.333

(2008)

17. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be

(a)
CHO
(b)
CH4O


(c)
CH3O
(d)
CH2O
(2008)


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 (2007)


The maximum number of molecules is present in

15 L of H2 gas at STP
5 L of N2 gas at STP
0.5 g of H2 gas
(d)  10 g of O2 gas.
(2004)


Which has maximum molecules?
(a)
7 g N2
(b)
2 g H2

(c)
16 g NO2
(d)
16 g O2  (2002)







Percentage of Se in peroxidase anhydrous enzyme is 0.5% by weight (at. wt. = 78.4) then minimum molecular weight of peroxidase anhydrous enzyme is

(a)
1.568 × 104
(b)
1.568 × 103

(c)
15.68
(d)
2.136 × 104

(2001)

Molarity of liquid HCl, if density of solution is

1.17 g/cc is

(a)
36.5
(b)
18.25


(c)
32.05
(d)
42.10
(2001)


Specific volume of cylindrical virus particle is 6.02 × 10–2 cc/g whose radius and length are

Å and 10 Å respectively. If NA = 6.02 × 1023, find molecular weight of virus.
(a) 15.4 kg/mol (b)  1.54 × 104 kg/mol
(c)  3.08 × 104 kg/mol   (d)  3.08 × 103 kg/mol (2001)

In quantitative analysis of second group in laboratory, H2S gas is passed in acidic medium for precipitation. When Cu2+ and Cd2+ react with KCN, then for product, true statement is
K2[Cu(CN)4] more soluble
K2[Cd(CN)4] less stable
K3[Cu(CN)2] less stable
(d)  K2[Cd(CN)3] more stable.
(2000)

Volume of CO2  obtained by the complete
decomposition of 9.85 g of BaCO3 is

(a)
2.24 L
(b)
1.12 L


(c)
0.84 L
(d)
0.56 L
(2000)


Oxidation numbers of A, B, C are +2, +5 and –2 respectively. Possible formula of compound is
(a)
A2(BC2)2
(b)
A3(BC4)2

(c)
A2(BC3)2
(d)
A3(B2C)2

(2000)

The number of atoms in 4.25 g of NH3 is approximately
(a)
4 × 1023
(b)
2
× 2023


(c)
1 × 1023
(d)
6
× 1023
(1999)


Given the numbers: 161 cm, 0.161 cm, 0.0161 cm. The number of significant figures for the three numbers is
3, 3 and 4 respectively

3, 4 and 4 respectively

3, 4 and 5 respectively

(d)  3, 3 and 3 respectively.
(1998)



(d) As+ (1998)

(d) 2 (1998)




Some Basic Concepts of Chemistry
3



Haemoglobin contains 0.334% of iron by weight. The molecular weight of haemoglobin is approximately 67200. The number of iron atoms (Atomic weight of Fe is 56) present in

one molecule of haemoglobin is

(a) 4 (b) 6 (c)  3



In the reaction,
4NH3(g) + 5O2(g) ® 4NO(g) + 6H2O(l)
when 1 mole of ammonia and 1 mole of O2 are made to react to completion :

All the oxygen will be consumed.

1.0 mole of NO will be produced.
1.0 mole of H2O is produced.
All the ammonia will be consumed. (1998)

Among the following which one is not paramagnetic? [Atomic numbers; Be = 4, Ne = 10, As = 33, Cl = 17]
(a) Ne2+ (b) Be+ (c)  Cl–

0.24 g of a volatile gas, upon vaporisation, gives

45 mL vapour at NTP. What will be the vapour density of the substance? (Density of H2 = 0.089)
95.93   (b) 59.93  (c)  95.39  (d) 5.993

(1996)

The amount of zinc required to produce 224 mL of H2 at STP on treatment with dilute H2SO4
will be

(a)  65 g
(b) 0.065 g (c)  0.65 g (d) 6.5 g


(1996)


The dimensions of pressure are the same as that of

force per unit volume

energy per unit volume

force

(d)  energy.
(1995)


The number of moles of oxygen in one litre of

air containing 21% oxygen by volume, under standard conditions, is

(a)
0.0093 mol
(b)
2.10 mol

(c)
0.186 mol
(d)
0.21 mol.


(1995)

The total number of valence electrons in 4.2 g
of N3– ion is (NA is the Avogadro’s number)
(a)
2.1
NA
(b)
4.2
NA


(c)
1.6
NA
(d)
3.2
NA
(1994)


A 5 molar solution of H2SO4 is diluted from 1


litre to a volume of 10 litres, the normality of the solution will be

(a)
1 N
(b)
0.1 N


(c)
5 N
(d)
0.5 N
(1991)


The number of gram molecules of oxygen in
6.02 × 1024 CO molecules is
(a) 10 g molecules (b)  5 g molecules

(c) 1 g molecules (d)  0.5 g molecules.

(1990)

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

(a)
10.8
(b)
10.2


(c)
11.2
(d)
10.0
(1990)


The molecular weight of O2 and SO2 are 32 and 64 respectively. At 15°C and 150 mmHg pressure, one litre of O2 contains ‘N’ molecules. The number of molecules in two litres of SO2 under the same conditions of temperature and pressure will be

(a)
N/2
(b)
N


(c)
2 N
(d)
4 N
(1990)


41)A metal oxide has the formula Z2O3. It can be reduced by hydrogen to give free metal and water. 0.1596 g of the metal oxide requires 6 mg
of hydrogen for complete reduction. The atomic weight of the metal is

(a) 27.9. (b)159.6
(c)79.8. (d)55.8
(1989)


42)Ratio of Cp and CV of a gas ‘X’ is 1.4. The
number of atoms of the gas ‘X’ present in 11.2 litres of it at NTP will be
(a)
6.02 × 1023
(b)
1.2 × 1023

(c)
3.01 × 1023
(d)
2.01 × 1023

(1989)

43)What is the weight of oxygen required for the

complete combustion of 2.8 kg of ethylene?

(a)  2.8 kg   (b) 6.4 kg  (c)  9.6 kg (d) 96 kg (1989)

44) The number of oxygen atoms in 4.4 g of CO2 is
(a)
1.2 × 1023
(b)
6 × 1022

(c)
6 × 1023
(d)
12 × 1023

(1989)

45. At S.T.P. the density of CCl4 vapour in g/L will be nearest to
(a) 6.87 (b) 3.42 (c)  10.26 (d) 4.57

(1988)

46) One litre hard water contains 12.00 mg Mg2+. Milli-equivalents of washing soda required to

remove its hardness is
(a)
1
(b)
12.16

(c)
1 × 10–3
(d)
12.16 × 10–3

(1988)



47. 1 cc N2O at NTP contains


2241.8 u10 22 atoms

224006.02 u10 23 molecules

1.32224 u10 23electrons

(d)  All the above.
(1988)

















































Answer Key





1.
(a)
2.
(b)
3.
(a)
4.
(c)
5.
(d)
6.
(c)
7.
(a)
8.
(a)
9.
(d)
10.
(b)

11.
(c)
12.
(b)
13.
(b)
14.
(b)
15.
(a)
16.
(b)
17.
(c)
18.
(d)
19.
(a)
20.
(b)

21.
(a)
22.
(c)
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(a)
24.
(c)
25.
(b)
26.
(b)
27.
(d)
28.
(d)
29.
(a)
30.
(a)

31.
(c)
32.
(b)
33.
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34.
(b)
35.
(a)
36.
(c)
37.
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38.
(b)
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(a)
40.
(c)

41.
(d)
42.
(a)
43.
(c)
44.
(a)
45.
(a)
46.
(a)
47.
(d)