Some Basic Concepts of Chemistry — JEE Main PYQs

Assume carbon burns according to following equation :
$2{\mathrm{C}}_{(\mathrm{s})}+{\mathrm{O}}_{2(\mathrm{g})}\to 2\mathrm{CO}(\mathrm{g})$
When 12 g carbon is burnt in 48 g of oxygen, the volume of carbon monoxide produced is ____
$\times 10^{-1}\mathrm{L}$ a …

On complete combustion, 0.492 g of an organic compound gave 0.792 g of ${\mathrm{CO}}_2$.

The % of carbon in the organic compound is ______ (Nearest integer)

Zinc reacts with hydrochloric acid to give hydrogen and zinc chloride. The volume of hydrogen gas produced at STP from the reaction of 11.5 g of zinc with excess HCl is ______ L (Nearest integer)
(Given : Molar mass of Zn is $65.4\mathrm{g}{\mathrm{mol}}^{-1}$ and Molar volume …

Consider the reaction
$4{\mathrm{HNO}}_3(l)+3\mathrm{KCl}(\mathrm{s})\to {\mathrm{Cl}}_2(\mathrm{g})+\mathrm{NOCl}(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(\mathrm{g})+3{\mathrm{KNO}}_3(\mathrm{s})$

The amount of ${\mathrm{HNO}}_3$ required to produce 110.0 g o …

In the given reaction,
$\mathrm{X}+\mathrm{Y}+3\mathrm{Z}\rightleftarrows {\mathrm{XYZ}}_3$
if one mole of each of X and Y with 0.05 mol of Z gives compound ${\mathrm{XYZ}}_3$. (Given: Atomic masses of $\mathrm{X},\mathrm{Y}$ and Z are 10, 20 and 30 amu, respectively).
The yie …

On complete combustion of 0.492 g of an organic compound containing C, H and O, 0.7938 g of ${\text{CO}}_2$ and 0.4428 g of ${\text{H}}_2\text{O}$ was produced. The % composition of oxygen in the compound is $\_\_\_\_$.

2 L of 0.2 M H₂SO₄ is reacted with 2 L of 0.1 M NaOH solution, the molarity of the resulting product Na₂SO₄ in the solution is _____ millimolar. (Nearest integer).

250 g solution of D-glucose in water contains $10.8\%$ of carbon by weight. The molality of the solution is nearest to
(Given: Atomic Weights are H, 1u ; C, 12u ; O, 16u)

${\mathrm{SO}}_2{\mathrm{Cl}}_2$ on reaction with excess of water results into acidic mixture
${\mathrm{SO}}_2{\mathrm{Cl}}_2+2{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{HCl}$
16 moles of NaOH is required for the complete neutralisation …

Hemoglobin contains $0.34\%$ of iron by mass. The number of Fe atoms in 3.3 g of hemoglobin is :
(Given : Atomic mass of Fe is $56\mathrm{u}$, ${\mathrm{N}}_{\mathrm{A}}$ is $6.022\times 10^{23}{\mathrm{mol}}^{-1}$)

A 10 g mixture of hydrogen and helium is contained in a vessel of capacity $0.0125{\mathrm{m}}^3$ at 6 bar and $27^{\circ }\mathrm{C}$. The mass of helium in the mixture is
____ g. (nearest integer)

Given : $\mathrm{R}=8.3{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$ (Atomic masse …

The normality of ${\mathrm{H}}_2{\mathrm{SO}}_4$ in the solution obtained on mixing 100 mL of $0.1\mathrm{M}{\mathrm{H}}_2{\mathrm{SO}}_4$ with 50 mL of 0.1 M NaOH is $\_\_\_\_$ $\times 10^{-1}\mathrm{N}$. (Nearest Integer)

56.0 L of nitrogen gas is mixed with excess of hydrogen gas and it is found that 20 L of ammonia gas is produced. The volume of unused nitrogen gas is found to be _____ L.

A sample of 4.5 mg of an unknown monohydric alcohol, $\mathrm{R}-\mathrm{OH}$ was added to methylmagnesium iodide. A gas is evolved and is collected and its volume measured to be 3.1 mL. The molecular weight of the unknown alcohol is ____ g/mol. [Nearest integer]

Chlorophyll extracted from the crushed green leaves was dissolved in water to make 2 L solution of Mg of concentration 48 ppm . The number of atoms of Mg in this solution is $\mathrm{x}\times 10^{20}$ atoms. The value of $x$ is ______. (Nearest Integer)
(Given : Atomic mass of M …

When 800 mL of 0.5 M nitric acid is heated in a beaker, its volume is reduced to half and 11.5 g of nitric acid is evaporated. The molarity of the remaining nitric acid solution is $x\times 10^{-2}$ M.
(Nearest Integer)
(Molar mass of nitric acid is $63{\mathrm{g}\mathrm{mol}}^{-1}$)

Compound A contains $8.7\%$ Hydrogen, $74\%$ Carbon and 17.3% Nitrogen. The molecular formula of the compound is,

Given : Atomic masses of $\mathrm{C},\mathrm{H}$ and N are 12, 1 and 14 amu respectively.

The molar mass of the compound A is …

100 g of an ideal gas is kept in a cylinder of 416 L volume at $27^{\circ }\mathrm{C}$ under 1.5 bar pressure. The molar mass of the gas is ______ $\mathrm{g}{\mathrm{mol}}^{-1}$. (Nearest integer)
(Given : $\mathrm{R}=0.083\mathrm{L}$ bar ${\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}$)

The complete combustion of 0.492 g of an organic compound containing 'C', 'H' and 'O' gives 0.793 g of $\mathrm{CO}{}_2$ and 0.442 g of $\mathrm{H}{}_2\mathrm{O}$. The percentage of oxygen composition in the organic compound is ______. (nearest integer)

116 g of a substance upon dissociation reaction, yields 7.5 g of hydrogen, 60 g of oxygen and 48.5 g of carbon. Given that the atomic masses of H, O and C are 1, 16 and 12 respectively. The data agrees with how many formulae of the following?
(A) ${\mathrm{CH}}_3\mathrm{COOH}$
( …

Using the rules for significant figures, the correct answer for the expression $\frac{0.02858\times 0.112}{0.5702}$ will be:

CNG is an important transportation fuel. When 100 g CNG is mixed with 208 g oxygen in vehicles, it leads to the formation of ${\mathrm{CO}}_2$ and ${\mathrm{H}}_2\mathrm{O}$ and produces large quantity of heat during this combustion, then the amount of carbon dioxide, produce …

The moles of methane required to produce 81 g of water after complete combustion is $\_\_\_\_$ $\times 10^{-2}$ mol. [nearest integer]

Production of iron in blast furnace follows the following equation

when 4.640 kg of ${\mathrm{Fe}}_3{\mathrm{O}}_4$ and 2.520 kg of CO are allo …

Geraniol, a volatile organic compound, is a component of rose oil. The density of the vapour is $0.46{\mathrm{gL}}^{-1}$ at $257^{\circ }\mathrm{C}$ and 100 mm Hg. The molar mass of geraniol is ______ (Nearest Integer)
[Given …

17.0 g of ${\mathrm{NH}}_3$ completely vapourises at $-33.42^{\circ }\mathrm{C}$ and 1 bar pressure and the enthalpy change in the process is $23.4{\mathrm{kJ}\mathrm{mol}}^{-1}$. The enthalpy change for the vapourisation of 85 g of ${\mathrm{NH}}_3$ under the same conditions is ______ k …

A commercially sold conc. HCl is $35\%\mathrm{HCl}$ by mass. If the density of this commercial acid is 1.46 $\mathrm{g}/\mathrm{mL}$, the molarity of this solution is :
(Atomic mass : $\mathrm{Cl}=35.5\mathrm{amu},\mathrm{H}=1\mathrm{amu}$ )

An evacuated glass vessel weighs 40.0 g when empty, 135.0 g when filled with a liquid of density $0.95\mathrm{g}{\mathrm{mL}}^{-1}$ and 40.5 g when filled with an ideal gas at 0.82 atm at 250 K . The molar mass of the gas in $\mathrm{g}{\mathrm{mol}}^{-1}$ is :
(Given : …

On complete combustion 0.30 g of an organic compound gave 0.20 g of carbon dioxide and 0.10 g of water. The percentage of carbon in the given organic compound is ______ (Nearest Integer)

Two elements A and B which form 0.15 moles of ${\mathrm{A}}_2\mathrm{B}$ and ${\mathrm{AB}}_3$ type compounds. If both ${\mathrm{A}}_2\mathrm{B}$ and ${\mathrm{AB}}_3$ weigh equally, then the atomic weight of A is
____ times of atomic weight of B .

${\mathrm{N}}_{2(\mathrm{g})}+3{\mathrm{H}}_{2(\mathrm{g})}\rightleftharpoons 2{\mathrm{NH}}_{3(\mathrm{g})}$

20 g 5 g

Consider the above reaction, the limiting reagent of the reaction and number of moles of ${\mathrm{NH}}_3$ formed respectively are:

In bromination of Propyne, with Bromine 1, 1, 2, 2-tetrabromopropane is obtained in 27% yield. The amount of 1,1,2,2 tetrabromopropane obtained from 1 g of Bromine in this reaction is ____ × 10⁻¹ g. (Nearest integer)
(Molar Mass : Bromine = 80 g/mol)

If a rocket runs on a fuel (${\mathrm{C}}_{15}{\mathrm{H}}_{30}$) and liquid oxygen, the weight of oxygen required and ${\mathrm{CO}}_2$ released for every litre of fuel respectively are: (Given: density of the fuel is $0.756\mathrm{g}/\mathrm{mL}$)

120 g of an organic compound that contains only carbon and hydrogen gives 330 g of ${\mathrm{CO}}_2$ and 270 g of water on complete combustion. The percentage of carbon and hydrogen, respectively are.

At 300 K, a sample of 3.0 g of gas A occupies the same volume as 0.2 g of hydrogen at 200 K at the same pressure. The molar mass of gas A is _____ g ${\mathrm{mol}}^{-1}$ (nearest integer) Assume that the behaviour of gases as ideal. (Given: The molar mass of hydrogen …

The number of N atoms is 681 g of ${\mathrm{C}}_7{\mathrm{H}}_5{\mathrm{N}}_3{\mathrm{O}}_6$ is $\mathrm{x}\times 10^{21}$. The value of x is ____ ( ${\mathrm{N}}_{\mathrm{A}}=6.02\times 10^{23}{\mathrm{mol}}^{-1}$ ) (Nearest Integer)

1 L aqueous solution of ${\mathrm{H}}_2{\mathrm{SO}}_4$ contains 0.02 $\mathrm{m}\mathrm{mol}{\mathrm{H}}_2{\mathrm{SO}}_4.50\%$ of this solution is diluted with deionized water to give 1 L solution (A). In solution (A), 0.01 m mol of ${\mathrm{H}}_2{\mathrm{SO}}_4$ …

4.5 g of compound A (MW = 90) was used to make 250 mL of its aqueous solution. The molarity of the solution in M is $x\times 10^{-1}$. The value of x is ____. (Rounded off to the nearest integer)

An aqueous KCl solution of density $1.2\mathrm{g}{\mathrm{mL}}^{-1}$ has a molality of $3.30\mathrm{mol}{\mathrm{kg}}^{-1}$. The molarity of the solution in $\mathrm{mol}{\mathrm{L}}^{-1}$ is ______ (Nearest integer)
[Molar mass of KCl = 74.5]

A chloro compound "A"
(i) forms aldehydes on ozonolysis followed by the hydrolysis.
(ii) when vaporized completely 1.53 g of A, gives 448 mL of vapour at STP.

The number of carbon atoms in a molecule of compound $A$ is $\_\_\_\_$.

100 mL of ${\mathrm{Na}}_3{\mathrm{PO}}_4$ solution contains 3.45 g of sodium. The molarity of the solution is $\_\_\_\_$ $\times 10^{-2}\mathrm{mol}{\mathrm{L}}^{-1}$. (Nearest integer)
[Atomic Masses - Na : …

250 mL of 0.5 M NaOH was added to 500 mL of 1 M HCl. The number of unreacted HCl molecules in the solution after complete reaction is ____ $\times 10^{21}$ (Nearest integer)
$\left({\mathrm{N}}_{\mathrm{A}}=6.022\times 10^{23}\right)$

The formula of a gaseous hydrocarbon which requires 6 times of its own volume of ${\mathrm{O}}_2$ for complete oxidation and produces 4 times its own volume of ${\mathrm{CO}}_2$ is ${\mathrm{C}}_{\mathrm{x}}{\mathrm{H}}_{\mathrm{y}}$. The value of y is

1.86 g of aniline completely reacts to form acetanilide. 10% of the product is lost during purification. Amount of acetanilide obtained after purification (in g) is $\_\_\_\_$ $\times 10^{-2}$.

The volume occupied by 4.75 g of acetylene gas at $50^{\circ }\mathrm{C}$ and 740 mmHg pressure is $\_\_\_\_$ L
(Rounded off to the nearest integer)
[Given $\mathrm{R}=0.0826\mathrm{L}\mathrm{atm}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}$]

4g equimolar mixture of NaOH and ${\mathrm{Na}}_2{\mathrm{CO}}_3$ contains xg of NaOH and y g of ${\mathrm{Na}}_2{\mathrm{CO}}_3$. The value of $x$ is ______ g.(Nearest Integer)

100 g of propane is completely reacted with 1000 g of oxygen. The mole fraction of carbon dioxide in the resulting mixture is $x\times 10^{-2}$. The value of $x$ is ____. (Nearest integer)
[Atomic weight : $\mathrm{H}=1.008;\mathrm{C}=12.00;\mathrm{O}=16.00$]

Complete combustion of 1.80 g of an oxygen containing compound $({\mathrm{C}}_{\mathrm{x}}{\mathrm{H}}_{\mathrm{y}}{\mathrm{O}}_{\mathrm{z}})$ gave 2.64 g of ${\mathrm{CO}}_2$ and 1.08 g of ${\mathrm{H}}_2\mathrm{O}$. The percentage of oxygen in the organic compound is

Methylation of 10 g of benzene give 9.2 g of toluene. Calculate the percentage yield of toluene ______. (Nearest integer)

If the concentration of glucose ($\mathrm{C}{}_6\mathrm{H}{}_{12}\mathrm{O}{}_6$) in blood is $0.72{\text{ g L}}^{-1}$, the molarity of glucose in blood is ______ $\times 10^{-3}\text{ M}$. (Nearest integer)
(Given: Atomic mass of $\mathrm{C}=12$, $\mathrm{H}=1$, $\mathrm{O}=16$ u)