Some Basic Concepts in Chemistry MCQ Questions & Answers in Physical Chemistry | Chemistry
Learn Some Basic Concepts in Chemistry MCQ questions & answers in Physical Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
191.
How many significant figures are present in 0.010100 × 103 ?
A
7
B
5
C
3
D
10
Answer :
5
0.010100 × 103 contains 5 significant figures.
192.
An aqueous solution of oxalic acid dihydrate
contains its 6.3 $$g$$ in 250 $$mL.$$ The volume of 0.1 $$N$$ $$NaOH$$ required to completely neutralize 10 $$mL$$ of
this solution
193.
In a compound $$C,$$ $$H$$ and $$N$$ atoms are present in 9 : 1 : 3.5 by weight. Molecular weight of compound is 108. Molecular formula of compound is
194.
In a mixture of gases, the volume content of a gas is $$0.06\% $$ at $$STP.$$ Calculate the number of molecules of the gas in $$1\,L$$ of the mixture.
A
$$1.613 \times {10^{23}}$$
B
$$6.023 \times {10^{23}}$$
C
$$1.61 \times {10^{27}}$$
D
$$1.61 \times {10^{19}}$$
Answer :
$$1.61 \times {10^{19}}$$
Volume of gas in $$1\,L = \frac{{0.06}}{{100}} = 6 \times {10^{ - 4}}L$$
Number of molecules of $$C{O_2} = n \times {N_A}$$
$$\frac{{6 \times {{10}^{ - 4}}}}{{22.4}} \times 6.023 \times {10^{23}} = 1.61 \times {10^{19}}$$
195.
What will be the molality of chloroform in the water sample which contains $$15\,ppm$$ chloroform by mass ?
196.
The reaction, $$3Cl{O^ - }\left( {aq} \right) \to ClO_3^ - \left( {aq} \right) + 2C{l^ - }\left( {aq} \right),$$ is an example of
A
oxidation reaction
B
reduction reaction
C
disproportionation reaction
D
decomposition reaction
Answer :
disproportionation reaction
TIPS/Formulae :
(i) In a disproportionation reaction same element undergoes oxidation as well as reduction during the reaction.
(ii) In decomposition reaction a molecule breaks down to more than one atoms or molecules
$$\mathop {3ClO_{\left( {aq} \right)}^ - }\limits^{ + 1} \mathop { \to ClO_3^ - }\limits^{ + 5} + \mathop {2Cl_{\left( {aq} \right)}^ - }\limits^{ - 1} $$
It is disproportionation reaction because $$Cl$$ is both oxidised $$\left( {{\text{ + 1}}\,{\text{to}}\,{\text{ + 5}}} \right)$$ and reduced $$\left( {{\text{ + 1}}\,{\text{to}}\, - 1} \right)$$ during reaction.
197.
Haemoglobin contains $$0.33\% $$ of iron by weight. The molecular weight of haemoglobin is approximately $$67200 g.$$ The number of iron atoms $$\left( {{\text{at}}{\text{.}}\,{\text{weight of}}\,Fe\,{\text{is}}\,\,56} \right)$$ present in one molecule of haemoglobin are
A
1
B
6
C
4
D
2
Answer :
4
$$\because \,0.33\% \,$$ of iron by weight means $$100g$$ of haemoglobin has $$0.33 g$$ of iron
$$100 g$$ of haemoglobin contains iron $$= 0.33 g$$
∴ $$67200 g$$ of haemoglobin contains iron
$$\eqalign{
& = \frac{{0.33 \times 67200}}{{100}}g \cr
& = 221.76\,g\,{\text{of}}\,Fe \cr
& {\text{Number of }}Fe{\text{ - }}atoms \cr
& = \frac{{221.76}}{{56}} \cr
& = 3.96 \approx 4 \cr} $$
198.
In the final answer of the expression $$\frac{{\left( {29.2 - 20.2} \right)\left( {1.79 \times {{10}^5}} \right)}}{{1.37}}$$ the number of significant figures is
A
1
B
2
C
3
D
4
Answer :
3
On calculation we find
$$\eqalign{
& \frac{{\left( {29.2 - 20.2} \right)\left( {1.79 \times {{10}^5}} \right)}}{{1.37}} \cr
& = 1.17 \times {10^6} \cr} $$
As the least precise number contains 3 significant figures, therefore answer should also contains 3 significant figures.
199.
Few quantities with their units are listed below. Mark the units which are not correctly matched.
(i) Density : $$kg\,\,{m^{ - 3}}$$
(ii) Velocity of light : $$m\,\,{s^{ - 1}}$$
(iii) Planck's constant : $${J^{ - 1}}{s^{ - 1}}$$
(iv) Acceleration : $$m\,\,{s^{ - 2}}$$
(v) Force : $$kg\,\,m$$
200.
$$10$$ $$mL$$ of $$2$$ $$M$$ $$NaOH$$ solution is added to $$200$$ $$mL$$ of $$0.5$$ $$M$$ of $$NaOH$$ solution. What is the final concentration ?