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Some Basic Concepts of Chemistry — NEET UG Chemistry PYQs

370 previous year questions from Some Basic Concepts of Chemistry with answers and solutions. Numbered list, year tags, and one-tap solutions — built for serious JEE / NEET practice.

370 questionsChemistrySolutions on every page
1

Calculate the mass of potassium chlorate required to liberate 6.72 dm ^3 of oxygen at STP. [Molar mass of potassium chlorate = 122.5 g mol ⁻¹ ]

MHT CET Medical 2026 Solution View → 2

Find the mass of lime obtained by heating 500 g of 90 % pure lime stone. [Molar masses Ca =40 g/mol, O =16 g/mol & C =12 g/mol]

MHT CET Medical 2026 Solution View → 3

A coordination complex contains 2.6 % of Mg. Find the number of Mg atoms in 5.0 g of this sample. (gram atomic mass of Mg = 24 g )

MHT CET Medical 2026 Solution View → 4

Calculate the number of moles and molecules of chlorine in 4.48 dm ^3 of chlorine at STP.

MHT CET Medical 2026 Solution View → 5

What is the gram atomic mass of an element whose mass of one atom is 3.9853 10⁻²³ g ?

MHT CET Medical 2026 Solution View → 6

Calculate the total mass and number of molecules present in 3 moles of benzene.

MHT CET Medical 2026 Solution View → 7

Which of the following gases has high vapour density at same temperature and pressure?

MHT CET Medical 2026 Solution View → 8

What is the number of moles of Cl atoms present in n moles of tear gas and in n moles of mustard gas respectively?

MHT CET Medical 2026 Solution View → 9

Calculate the number of atoms in 52 moles of argon.

MHT CET Medical 2026 Solution View → 10

Find the mass of 1 molecule of H ₂ SO ₄ in grams.

MHT CET Medical 2026 Solution View → 11

Which of the following compounds has maximum number of molecules ?

MHT CET Medical 2026 Solution View → 12

Calculate the number of carbon atoms present in 11 g of carbon dioxide.

MHT CET Medical 2026 Solution View → 13

The numbers 17.0145 and 21.0235 were rounded to three figures after the decimal point. The resulting numbers, respectively, are

NEET 2026 Solution View → 14

When 1 dm ^3 of CO ₂ gas is passed over hot coke, the volume of gaseous mixture after complete reaction at STP becomes 1.4 dm ^3 . The composition of the gaseous mixture at STP is

NEET 2026 Solution View → 15

The number of hydrogen atoms present in 5.4 g of urea is : (Given : Molar mass of urea : 60 g mol ⁻¹ , N_A : 6.022 10²³ particles mol ⁻¹ )

NEET 2026 Solution View → 16

The amount of carbon dioxide evolved upon complete combustion of 116 g of n -butane is (Given: atomic mass in amu H =1 , C =12 and O =16 )

NEET 2026 Solution View → 17

Among the following choose the ones with equal number of atoms. A. 212 g of Na ₂ CO ₃( ~s ) [molar mass =106 ~g ] B. 248 g of Na ₂ O (s) [molar mass =62 ~g ] C. 240 g of NaOH ( s )

NEET 2025 Solution View → 18

Dalton's Atomic theory could not explain which of the following?

NEET 2025 Solution View → 19

1.0 g of H ₂ has same number of molecules as in:

NEET 2024 Solution View → 20

1 gram of sodium hydroxide was treated with 25 mL of 0.75 M HCl solution, the mass of sodium hydroxide left unreacted is equal to

NEET 2024 Solution View → 21

A compound X contains 32 % of A, 20 % of B and remaining percentage of C . Then, the empirical formula of X is : (Given atomic masses of A=64 ; B=40 ; C=32 u )

NEET 2024 Solution View → 22

The highest number of helium atoms is in

NEET 2024 Solution View → 23

The density of 1 M solution of a compound ' X ' is 1.25 ~g ~mL ⁻¹ . The correct option for the molality of solution is (Molar mass of compound X=85 ~g )

NEET 2023 Solution View → 24

The right option for the mass of CO 2 produced by heating 20   g of 20 % pure limestone is (Atomic mass of Ca = 40 ) CaCO 3 → 1200   K CaO + CO 2

NEET 2023 Solution View → 25

The density of the solution is 2.15 ~g ~mL ⁻¹ , then mass of 2.5 ~mL solution in correct significant figures is

NEET 2022 Solution View → 26

What mass of 95 % pure CaCO 3 will be required to neutralise 50   mL of 0 . 5   M   HCl solution according to the following reaction? CaCO 3 s + 2 HCl aq → CaC

NEET 2022 Solution View → 27

An organic compound contains 80 % (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is: [Atomic wt. of C is 12 and o

NEET 2021 Solution View → 28

Which one of the followings has maximum number of atoms?

NEET 2020 Solution View → 29

One mole of carbon atom weighs 12 g , the number of atoms in it is equal to, (Mass of carbon - 12 is 1 . 9926 × 10 - 23 g

NEET 2020 Solution View → 30

Find empirical formula of the compound containing a metal, M=68 % (atomic mass =34) and remaining 32 % oxygen.

AIIMS 2019 Solution View → 31

In a chemical reaction, A+B A B , if B is acting as a limiting reagent, then choose the correct option.

AIIMS 2019 Solution View → 32

Calculate molarity of 63 % w / w HNO ₃ solution if density is 1.4 ~g / mL .

AIIMS 2019 Solution View → 33

An element with mass number 81 contains 31.7 % more neutrons as compared to protons. It symbol is

JIPMER 2019 Solution View → 34

If molarity of Cu ⁺² ions is 3 10⁻⁴ express this in ppm

JIPMER 2019 Solution View → 35

2 KHCO ₃ + CO ₂+ H ₂ O find amount of gases formed (in lit). When amount of KHCO ₃ is 33 gm .

JIPMER 2019 Solution View → 36

Assertion : One mole of NaCl contains 6.023 10²³ formula units of sodium chloride. Reason : 58.5 ~g of NaCl also contains 6.023 10²³ formula units of NaCl .

AIIMS 2018 Solution View → 37

The normality of 10 % H ₂ SO ₄ solution having density 1.1 ~g / cc is

AIIMS 2018 Solution View → 38

Mixture of two bivalent metals A and B having mass 2 ~g when dissolved in HCl at STP, 2.24 ~L H ₂ is evolved. What is the mass of A present in mixture? (Atomic mass of A=15 u , B=3

AIIMS 2018 Solution View → 39

A compound, containing only carbon, hydrogen and oxygen has a molecular weight of 44 . On complete oxidation, it is converted into a compound of molecular weight is 60 . The origin

JIPMER 2018 Solution View → 40

In which case the number of molecules of water maximum?

NEET 2018 Solution View → 41

A mixture of 2 . 3   g formic acid and 4 . 5   g oxalic acid is treated with concentrate H 2 SO 4 . The evolved gaseous mixture is passed through KOH pellets. What will b

NEET 2018 Solution View → 42

The normality of 10 %( ~W / V ) of acetic acid is

JIPMER 2017 Solution View → 43

The volume of water to be added to 100 cm ^3 of 0.5 NH ₂ SO ₄ to get decinormal concentraction is

JIPMER 2017 Solution View → 44

Combustion of glucose takes place according to the equation, C ₆ H ₁₂ O ₆+6 O ₂ 6 CO ₂+6 H ₂ O H=-72 k - cal The energy required for combustion of 1.6 g of glucose is

JIPMER 2017 Solution View → 45

10 ~mL of liquid carbon disulphide (specific gravity 2.63) is burnt in oxygen. Find the volume of the resulting gases measured at STP.

AIIMS 2016 Solution View → 46

Solid NaHCO ₃ will be neutralised by 40.0 mL of 0.1 M H ₂ SO ₄ solution. What would be the weight of solid NaHCO ₃ in gram?

JIPMER 2016 Solution View → 47

11.2 L of gas at STP Weight 14 g . The gas would be

JIPMER 2016 Solution View → 48

Suppose the elements X and Y combine to form two compounds X Y 2 and X 3 Y 2 . When 0 . 1   mole of X Y 2 weighs 10   g and 0 . 05   mole of X 3 Y 2 weighs 9  

NEET 2016 Solution View → 49

How many significant figures are present in 0.0000135 ?

AIIMS 2015 Solution View → 50

The amount of BaSO ₄ precipitated on mixing BaCl ₂(0.5 M ) with H ₂ SO ₄(1 M ) will correspond to

AIIMS 2015 Solution View → 51

Assertion: One mole of NaCl contains 6.023 10²³ molecules of sodium chloride. Reason : 58.5 ~g of NaCl also contains 6.023 10²³ molecules of NaCl .

AIIMS 2015 Solution View → 52

Which of the following is correctly arranged in order of increasing weight?

JIPMER 2015 Solution View → 53

The number of water molecules is maximum in

NEET 2015 Solution View → 54

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 samp

NEET 2015 Solution View → 55

What is mole fraction of the solute in a 1.00 m aqueous solution?

NEET 2015 Solution View → 56

If Avogadro number N A , is changed from 6.022 × 10 23   m o l - 1 to 6.022 × 10 20   m o l - 1 , this would change:

NEET 2015 Solution View → 57

What is the mass of the precipitate formed when 50 mL of 16.9 % solution of A g N O 3 is mixed with 50 mL of 5.8 % NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)

NEET 2015 Solution View → 58

A mixture of gases contains H 2 and O 2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two gases in the mixture?

NEET 2015 Solution View → 59

The number of atoms in 52 ~g of He is

AIIMS 2014 Solution View → 60

When 22.4 litres of H 2 g is mixed with 11.2 litres of C l 2 g , each at STP, the moles of H C l g formed is equal to

NEET 2014 Solution View → 61

1.0   g of magnesium is burnt with 0.56   g O 2 in a closed vessel. Which reaction is left in excess and how much? (At, wt. M g = 24 ;     O = 16 )

NEET 2014 Solution View → 62

Strength of H ₂ O ₂ is 15.18 ~g ~L ⁻¹ , then it is equal to

AIIMS 2013 Solution View → 63

In an experiment it is shown that 10 ml of 0.05 M solution of chloride required 10 ml of 0.1 M solution of AgNO ₃ , which of the following will be the formula of the chloride ( X s

NEET 2013 Solution View → 64

0.1 mol HCl is equal to

JIPMER 2011 Solution View → 65

Mole fraction of the solute in a 1.00 molal aqueous solution is

NEET 2011 Solution View → 66

Which has the maximum number of molecules among the following?

NEET 2011 Solution View → 67

100 ~cm ^3 of a given sample of H ₂ O ₂ gives 1000 ~cm ^3 of O ₂ at S.T.P. The given sample is

AIIMS 2010 Solution View → 68

When 25 ~g of Na ₂ SO ₄ is dissolved in 10^3 ~kg of solution, its concentration will be

AIIMS 2010 Solution View → 69

Stomach acid, a dilute solution of HCl in water, can be neutralized by reaction with sodium hydrogen carbonate, NaHCO _ 3(a q) + HCl _ (a q) NaCl _ (a q) + H ₂ O _ (l) + CO _ 2(g)

AIIMS 2010 Solution View → 70

Assertion : The molality of the solution does not change with change in tempe-rature. Reason : The molality is expressed in units of moles per 1000 ~g of solvent.

AIIMS 2010 Solution View → 71

The number of atoms in 0.1 mole of a triatomic gas is ( N _ A =6.02 10²³ ~mol ⁻¹ )

NEET 2010 Solution View → 72

What is the molarity of H ₂ SO ₄ solution that has a density of 1.84 ~g / cc at 35^ C and contains 98 % by weight?

AIIMS 2009 Solution View → 73

To a 25 ~mL H ₂ O ₂ solution, excess of acidified solution of KI was added. The iodine liberated required 20 ~mL of 0.3 ~N Na ₂ ~S ₂ O ₃ solution. The volume strength of H ₂ O ₂ so

AIIMS 2009 Solution View → 74

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

NEET 2009 Solution View → 75

Assertion : When a concentrated solution is diluted by adding more water, molarity of the solution remains unchanged. Reason : Product of moles of a solute and volume is equal to t

AIIMS 2008 Solution View → 76

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

AIIMS 2008 Solution View → 77

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

NEET 2008 Solution View → 78

What volume of oxygen gas ( O ₂ ) measured at 0^ C and 1 ~atm , is needed to burn completely 1 ~L of propane gas ( C ₃ H ₈ ) measured under the same conditions?

NEET 2008 Solution View → 79

Number of moles of MnO ₄⁻ required to oxidise one mole of ferrous oxalate completely in acidic medium will be

NEET 2008 Solution View → 80

What volume of oxygen gas ( O ₂ ) measured at 0^ C and 1 atm, is needed to burn completely 1 ~L of propane gas ( C ₃ H ₈ ) measured under the same conditions?

NEET 2008 Solution View → 81

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

NEET 2008 Solution View → 82

Volume occupied by one molecule of water (density .=1 ~g ~cm ⁻³ ) is

NEET 2008 Solution View → 83

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

NEET 2008 Solution View → 84

The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 g of aluminium metal from bauxite by the Hall process is (Atomic mass Al =27 )

JIPMER 2007 Solution View → 85

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

NEET 2007 Solution View → 86

Concentrated of aqueous sulphuric acid is 98 % H ₂ SO ₄ by mass and has a density of 1.80 ~g ~mL ⁻¹ Volume of acid required to make one litre of 0.1 M H ₂ SO ₄ solution is:

NEET 2007 Solution View → 87

Total number of atoms represented by the compound CuSO ₄ 5 H ₂ O is :

JIPMER 2006 Solution View → 88

The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 ~kg of a aluminium metal from bauxite by the Hall process is: (Atomic mass : A1 = 27)

NEET 2005 Solution View → 89

4.5 ~g of aluminium (at mass 27 amu ) is deposited at cathode from Al ³⁺ solution by a certain quality of electric charge. The volume of hydrogen produced at STP from H ⁺ ions in s

NEET 2005 Solution View → 90

The mole friction of the solute in one molal aqueous solution is:

NEET 2005 Solution View → 91

Volume of CO ₂ obtained from complete decomposition of 20 ~g CaCO ₃ at STP is

JIPMER 2004 Solution View → 92

Which of the following, is not a unit of pressure?

JIPMER 2004 Solution View → 93

The significant figures in 1.0024,1.240 and 0.0020 are respectively

JIPMER 2004 Solution View → 94

The maximum number of molecules is present in:

NEET 2004 Solution View → 95

In Haber process 3 litres of dihydrgen and 30 litres of dinitrogen were taken for reaction which yielded only 50 % of the expected product. What will be the composition of gaseous

NEET 2003 Solution View → 96

The weight of one molecule of a compound C ₆₀ H ₁₂₂ is

AIIMS 2002 Solution View → 97

Assertion : Atoms can neither be created nor destroyed. Reason : Under similar condition of temperature and pressure, equal volume of gases does not contain equal number of atoms.

AIIMS 2002 Solution View → 98

5 ~L of 1 M NaOH solution is mixed with 3 ~L of 0.5 M NaOH solution. Find out the molarity of the resultant solution:

NEET 2002 Solution View → 99

The percentage of C , H and N in an organic compound are 40 %, 13.3 % and 46.7 % , respectively, then the empirical formula is:

NEET 2002 Solution View → 100

Which has the maximum molecules?

NEET 2002 Solution View → 101

How many litres of ammonia gas at S.T.P. would be needed to prepare 100 ~mL of 2.5 M ammonium hydroxide solution?

AIIMS 2001 Solution View → 102

If 0.189 ~g of a chlorine containing organic compound gave 0.287 ~g of silver chloride, then the percentage of chlorine in the organic compound is

AIIMS 2001 Solution View → 103

What is the significance of zeros that precede the first non-zero digit in a number?

NEET Solution View → 104

How are non-zero digits treated in determining the number of significant figures?

NEET Solution View → 105

What is the unit of measurement for atomic mass in the present system?

NEET Solution View → 106

How many molecules of dioxygen (O 2 ) are required for the combustion of one molecule of methane (CH 4 ) in the given reaction?

NEET Solution View → 107

What is used to count entities at the microscopic level, such as atoms and molecules?

NEET Solution View → 108

What element serves as the standard for the present system of atomic masses?

NEET Solution View → 109

What is the mass of one mole of a substance in grams called?

NEET Solution View → 110

Who formulated the Law of Conservation of Mass?

NEET Solution View → 111

What is the Avogadro constant expressed in the unit mol–1 called?

NEET Solution View → 112

How was the Avogadro number determined precisely?

NEET Solution View → 113

How can Molality be defined?

NEET Solution View → 114

How is volume defined?

NEET Solution View → 115

What was the basis for assigning mass values to elements in the nineteenth century?

NEET Solution View → 116

What is the mass of 2 g of hydrogen gas in terms of molecules?

NEET Solution View → 117

What is a volumetric flask used for?

NEET Solution View → 118

Why is it necessary to consider the existence of isotopes and their relative abundances when calculating the average atomic mass of an element?

NEET Solution View → 119

What is the product of the combustion of methane?

NEET Solution View → 120

How many elementary entities are contained in one mole?

NEET Solution View →
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