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NEET Previous year Chemistry Questions Some Basic Concepts of Chemistry

3. 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                                                           (2014)

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

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

4. What volume of oxygen gas (O2) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane gas (C3H8) measured under the same conditions? (2008)

(a) 5 L                     (b) 10 L

(c) 7 L                     (d) 6 L

8. 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   (2007)

(a) 201 amu              (b) 202 amu

(c) 199 amu              (d) 200 amu

10. Which one of the followings has maximum number of atoms? (NEET 2020)

(a) 1 g of Ag(s) [Atomic mass of Ag = 108]

(b) 1 g of Mg(s) [Atomic mass of Mg = 24]

(c) 1 g of O2(g) [Atomic mass of O = 16]

(d) 1 g of Li(s) [Atomic mass of Li = 7]

11. In which case is number of molecules of water maximum?   (NEET 2018)

(a) 18 mL of water

(b) 0.18 g of water

(c) 0.00224 L of water vapors at 1 atm and 273 K

(d) 10–3 mol of water

12. 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               (NEET-II 2016)

(a) 40, 30            (b) 60, 40

(c) 20, 30            (d) 30, 20

13. If Avogadro number NA, is changed from 6.022 × 1023 mol –1 to 6.022 × 1020 mol–1, this would change                                                                      (2015)

(a) The mass of one mole of carbon

(b) The ratio of chemical species to each other in a balanced equation

(c) The ratio of elements to each other in a compound

(d) The definition of mass in units of grams

14. The number of water molecules is maximum in                     (2015)

(a) 1.8 gram of water

(b) 18 gram of water

(c) 18 moles of water

(d) 18 molecules of water.

15. 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?              (2015)

(a) 16 : 1                          (b) 2 : 1

(c) 1 : 4                            (d) 4 : 1

16. Which has the maximum number of molecules among the following?  (2011)

(a) 44 g CO2                (b) 48 g O3

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

17. The number of atoms in 0.1 mol of a triatomic gas is            (2010)

(NA = 6.02 × 1023 mol–1)

(a) 6.026 × 1022               (b) 1.806 × 1023

(c) 3.600 × 1023               (d) 1.800 × 1022

29. 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    (2008)        

(a) CHO                           (b) CH4O

(c) CH3O                         (d) CH2O

32. The number of moles of hydrogen molecules required to produce 20 moles of ammonia through Haber’s process is                                      (NEET 2019)                 

(a) 40                   (b) 10

(c) 20                   (d) 30

33. The density of 2 M aqueous solution of NaOH is 1.28 g/cm3. The molality of the solution is [Given that molecular mass of NaOH = 40 g mol–1] (NEET 2019)

(a) 1.20 m             (b) 1.56 m

(c) 1.67 m            (d) 1.32 m

34. A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H2SO4. The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be                                     (NEET 2018)

(a) 1.4                 (b) 3.0

(c) 2.8                (d) 4.4

35. What is the mass of the precipitate formed when50 mL of 16.9% solution of AgNO3 is mixed with 50 mL of 5.8% NaCl solution?                   (2015)

(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

36. 20.0 g of a magnesium carbonate sample Decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage? purity of magnesium carbonate in the sample?                                       (2015)

    (At. wt. of Mg = 24)

(a) 96                          (b) 60

(c) 84                           (d) 75