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Some basic concepts of chemistry MCQ





Multiple Choice Questions

Question 1
Which of the following terms are unitless?
(a) Molality
(b) Molarity
(c) Mole fraction
(d) Mass percent

Question 2
16 g of oxygen has same number of molecules as in
(a) 16 g of CO
(b) 28 g of $N_2$
(c) 14 g of $N_2$
(d) 1.0 g of $H_2$

Question 3
Number of significant Figures in the numer 1.065
(a) 3
(b) 4
(c) 2
(d) 1

Question 4
How many moles of atom are contained in 32.7 g of Zn
(a) .200
(b) .500
(c) 1.50
(d) .0118

Question 5
What will be the molality of the solution containing 18.25 g of HCl gas in 500 g of water?
(a) 0.1 m
(b) 1 M
(c) 0.5 m
(d) 1 m

Question 6
Calculate the number of Moles of $Cu(C_2H_3O_2)_2$ present in 200 g
(a) 1.1 mol
(b) 1 mol
(c) .9 mol
(d) 1.2 mol

Question 7
The percentage of Carbon is $Ca(HCO_3)_2$ is
(a) 15%
(b) 1.8%
(c) 14.8%
(d) 15.2%

Question 8
Which of the following statements about a compound is incorrect?
(a) A molecule of a compound has atoms of different elements.
(b) A compound cannot be separated into its constituent elements by physical methods of separation.
(c) A compound retains the physical properties of its constituent elements.
(d) The ratio of atoms of different elements in a compound is fixed

Question 9
Calculate the standard molar volume of oxygen gas. The density of $O_2$ gas at NTP is 1.429g/L.
(a) 22.39litres
(b) 21.2 Litres
(c) 24 Litres
(d) None of the above

Question 10
Calculate the number of oxygen atoms in 50 g of CaCO_3.
(a) $6.033 \times 10^{23}$ atoms
(b) $9.033 \times 10^{23}$ atoms
(c) $8.033 \times 10^{23}$ atoms
(d) $3.033 \times 10^{23}$ atoms



Question 11
What will be the molarity of a solution, which contains 5.85 g of NaCl(s) per 500 mL?
(a) 4 mol/L
(b) 20 mol/L
(c) 0.2 mol/L
(d) 2 mol/L

Question 12
the mass of $2.044 \times 10^{23}$ carbon atoms.
(a) 12 g
(b) 36 g
(c) 24 g
(d) 48 g

Question 13
How many gram of solute is required to prepare 1.0 L of 1 M CaCl2.6H2O?
(a) 200 g
(b) 216 g
(c) 219 g
(d) None of the above

Question 14
Which of the following reactions is not correct according to the law of conservation of mass.
(a) $2Mg(s) + O_2(g) \rightarrow 2MgO(s)$
(b) $C_3H_8(g) + O_2(g) \rightarrow CO_2(g) + H_2O(g)$
(c) $P_4(s) + 5O_2(g) \rightarrow P_4O_{10}(s)$
(d) $CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O (g)$

Question 15
How many mL of water must be added to 200 mL of .65 M HCL to dilute the solution to .20 M
(a) 450 mL
(b) 400 mL
(c) 350 mL
(d) 500 mL

Question 16
The number of Gram molecules of oxygen in $6.02 \times 10^24$ CO molecules is
(a) 10 gm-molecules
(b) 5 gm-molecules
(c) 1 gm -molecules
(d) .5 gm-molecules

Question 17
Which of the following has the largest number of atoms
(a)0.5 g-atoms of Cu
(b)0.635 g Cu
(c) 0.25moles of Cu atoms
(d)1g of Cu

Question 18
A measured temperature on Fahrenheit scale is 200 °F. What will this reading be on Celsius scale?
(a) 40 °C
(b) 94 °C
(c) 93.3 °C
(d) 30 °C

Question 19
1 Mole of $CH_4$ contains
(a) $6.02 \times 10^{23}$ atoms of H
(b) 4 gm-atoms of hydrogen
(c) $1.81 \times 10^{23}$ molecules of $CH_4$
(d) 3g of Carbon

Question 20
Which of the following pairs have the same number of atoms?
(a) 16 g of $O_2$(g) and 4 g of $H_2$(g)
(b) 16 g of $O_2$ and 44 g of $CO_2$
(c) 28 g of $N_2$ and 32 g of $O_2$
(d) 12 g of C(s) and 23 g of Na(s)

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