Some Basic Concepts of Chemistry — JEE Main PYQs

The number of significant figures in $50000.020\times 10^{-3}$ is ______

The ${\mathrm{NaNO}}_3$ weighed out to make 50 mL of an aqueous solution containing $70.0\mathrm{mg}{\mathrm{Na}}^{+}$ per mL is ____ g. (Rounded off to the nearest integer)
[Given; Atomic weight in $\mathrm{g}{\mathrm{mol}}^{-1}$ - Na: 23; N: 14; O: 16]

Sodium oxide reacts with water to produce sodium hydroxide. 20.0 g of sodium oxide is dissolved in 500 mL of water. Neglecting the change in volume, the concentration of the resulting NaOH solution is ______ $\times 10^{-1}\mathrm{M}$. (Nearest integer)
[Atomic mass : …

The molarity of the solution prepared by dissolving 6.3 g of oxalic acid $\left({\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\cdot 2{\mathrm{H}}_2\mathrm{O}\right)$ in 250 mL of water in $\mathrm{mol}{\mathrm{L}}^{-1}$ is $x\times 10^{-2}$. The value of $x$ is ______. (Nearest …

The density of NaOH solution is 1.2 gm cm${}^{-3}$. The molality of this solution is ______ m.
(Round off to the Nearest integer)
[Use : Atomic masses : Na 23.0 u O: 16.0 u H: 1.0 u Density of $\mathrm{H}{}_2\mathrm{O}$: 1.0 g cm${}^{-3}$]

The pressure exerted by a non- reactive gaseous mixture of 6.4 g of methane and 8.8 g of carbon dioxide in a 10 L vessel at $27^{\circ }\mathrm{C}$ is ____ kPa .
(Round off to the nearest integer).
[ Assume gases are ideal, …

The mole fraction of a solute in a 100 molal aqueous solution is ______ $\times 10^{-2}$.
(Round off to the nearest integer).
[Given : Atomic masses : H : 1.0u, O : 16.0u]

Consider the complete combustion of butane, the amount of butane utilized to produce 72.0 g of water is $\times 10^{-1}\mathrm{g}$, (in nearest integer)

A home owner uses $4.00\times 10^3{\mathrm{m}}^3$ of methane $\left({\mathrm{CH}}_4\right)$ gas, (assume ${\mathrm{CH}}_4$ is an ideal gas) in a year to heat his home. Under the pressure of 1.0 atm and 300 K, mass of gas used is $x\times 10^5\mathrm{g}$. The val …

The number of significant figure in 0.00340 is ____.

If 80 g of copper sulphate ${\mathrm{CuSO}}_4\cdot 5{\mathrm{H}}_2\mathrm{O}$ is dissolved in deionised water to make 5 L of solution. The concentration of the copper sulphate solution is $x\times 10^{-3}\mathrm{mol}{\mathrm{L}}^{-1}$. The value of x is ____. [Atomic mas …

The number of atoms in 8 g of sodium is $\mathrm{x}\times 10^{23}$. The value of x is ______.
(Nearest integer)
[Given: ${\mathrm{N}}_{\mathrm{A}}=6.02\times 10^{23}{\mathrm{mol}}^{-1}$, Atomic mass of $\mathrm{Na}=23.0\mathrm{u}$]

Complete combustion of 750 g of an organic compound provides 420 g of CO₂ and 210 g of H₂O. The percentage composition of carbon and hydrogen in organic compound is 15.3 and ____ respectively. (Round off to the nearest Integer).

A 6.50 molal solution of $\mathrm{KOH}(\mathrm{aq})$ has a density of $1.89\mathrm{g}{\mathrm{cm}}^{-3}$. The molarity of the solution is ____ $\mathrm{mol}{\mathrm{dm}}^{-3}$. (Round off to the nearest Integer).
[Atomic masses : …

When 35 mL of 0.15 M lead nitrate solution is mixed with 20 mL of 0.12 M chromic sulphate solution, _____ $\times 10^{-5}$ moles of lead sulphate precipitate out.
(Round off to the nearest integer).

Consider the above reaction where 6.1 g of Benzoic acid is used to get 7.8 g of m - bromo benzoic acid. The percentage yield of the product is ______.
(Round off to the nearest integer).
[Given : Atomic masses : C : 12.0u, H:1.0u, O:16.0u, Br:80.0 u]

The number of chlorine atoms in 20 mL of chlorine gas at STP is ______ $\times 10^{21}$ (Round off to the nearest integer).
[Assume chlorine is an ideal gas at STP …

____ grams of 3-Hydroxy propanal ( $\mathrm{MW}=74$ ) must be dehydrated to produce 7.8 g of acrolein $(\mathrm{MW}=56)\left({\mathrm{C}}_3{\mathrm{H}}_4\mathrm{O}\right)$ if the percentage yield is 64 .
(Round off to the nearest integer).
[Given: Atomic masses : C: 12. …

Complete combustion of 3 g of ethane gives $x\times 10^{22}$ molecules of water. The value of $x$ is
____ . (Round off to the nearest integer).
[Use : ${\mathrm{N}}_{\mathrm{A}}=6.023\times 10^{23}$; Atomic masses in u : C:12.0,O:16.0; H:1.0]

Amongst the following statements, that which was not proposed by Dalton was

The ammonia $\left({\mathrm{NH}}_3\right)$ released on quantitative reaction of 0.6 g urea $\left({\mathrm{NH}}_2{\mathrm{CONH}}_2\right)$ with sodium hydroxide(NaOH) can be neutralized by

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve 10 ppm of iron in 100 kg of wheat is ______

Atomic weight : $\mathrm{Fe}=55.85;\mathrm{S}=32.00;\mathrm{O}=16.00$

${\mathrm{NaClO}}_3$ is used, even in spacecraft, to produce ${\mathrm{O}}_2$. The daily consumption of pure ${\mathrm{O}}_2$ by a person is 492 L at $1\mathrm{atm},300\mathrm{K}$. How much amount of ${\mathrm{NaClO}}_3$, in grams, is required to produce …

10.30 mg of ${\mathrm{O}}_2$ is dissolved into a liter of sea water of density $1.03\mathrm{g}/\mathrm{mL}$. The concentration of ${\mathrm{O}}_2$ in ppm is ____.

The molarity of ${\mathrm{HNO}}_3$ in a sample which has density $1.4$ $g/mL$ and mass percentage of $63\%$ is (Molecular Weight of ${\mathrm{HNO}}_3=63$)

The mass percentage of nitrogen in histamine is ____.

The volume strength of $8.9\mathrm{M}{\mathrm{H}}_2{\mathrm{O}}_2$ solution calculated at 273 K and 1 atm is ____.
$\overline{\left(\mathrm{R}=0.0821\mathrm{L}\mathrm{atm}{\mathrm{K}}^{-1}{\mathrm{mol}}^{-1}\right)}$ (rounded off to the nearest integer)

The strengths of 5.6 volume hydrogen peroxide (of density $1\mathrm{g}/\mathrm{mL}$) in terms of mass percentage and molarity (M), respectively, are:
(Take molar mass of hydrogen peroxide as $34\mathrm{g}/\mathrm{mol}$)

The volume (in mL ) of 0.1 N NaOH required to neutralise 10 mL of 0.1 N phosphinic acid is ____.

$6.023\times 10^{22}$ molecules are present in 10 g of a substance 'x'. The molarity of a solution containing 5 g of substance 'x' in 2 L solution is $\_\_\_\_$ $\times 10^{-3}$.

The average molar mass of chlorine is $35.5\mathrm{g}{\mathrm{mol}}^{-1}$. The ratio of ${}^{35}\mathrm{Cl}$ to ${}^{37}\mathrm{Cl}$ in naturally occurring chlorine is close to:

The minimum number of moles of ${\mathrm{O}}_2$ required for complete combustion of 1 mole of propane and 2 moles of butane is ____

A solution of two components containing ${\mathrm{n}}_1$ moles of the $1^{\text{st }}$ component and ${\mathrm{n}}^2$ moles of the $2^{\text{nd }}$ component is prepared. $M_1$ and $M_2$ are the molecular weights of component 1 and 2 respectively. If d is the de …

The mass of ammonia in grams produced when 2.8 kg of dinitrogen quantitatively reacts with 1 kg of dihydrogen is ____.

A 100 mL solution was made by adding 1.43 g of ${\mathrm{Na}}_2{\mathrm{CO}}_3.\times {\mathrm{xH}}_2\mathrm{O}$. The normality of the solution is 0.1 N . The value of x is ____
(The atomic mass of Na is $23\mathrm{g}/\mathrm{mol}$ )

The percentage composition of carbon by mole in methane is:

The strength of 11.2 volume solution of ${\mathrm{H}}_2{\mathrm{O}}_2$ is:
[Given that molar mass of $\mathrm{H}=1\mathrm{g}{\mathrm{mol}}^{-1}$ and $\mathrm{O}=16\mathrm{g}{\mathrm{mol}}^{-1}$]

For a reaction,
${\mathrm{N}}_2(\mathrm{g})+3{\mathrm{H}}_2(\mathrm{g})\to 2{\mathrm{NH}}_3(\mathrm{g})$; identify dihydrogen $\left({\mathrm{H}}_2\right)$ as a limiting reagent in the following reaction mixtures.

The mole fraction of a solvent in aqueous solution of a solute is 0.8. The molality (in mol ${\mathrm{kg}}^{-1}$) of the aqueous solution is

5 moles of $A{B}_2$ weigh $125\times 10^{-3}\mathrm{kg}$ and 10 moles of $A_2{B}_2$ weigh $300\times 10^{-3}\mathrm{kg}$. The molar mass of $A\left(M_A\right)$ and molar mass of $B\left(M_B\right)$ in $\mathrm{kg}{\mathrm{mol}}^{-1}$ are :

The minimum amount of ${\mathrm{O}}_2(\mathrm{g})$ consumed per gram of reactant is for the reaction :
(Given atomic mass: $\mathrm{Fe}=56,\mathrm{O}=16,\mathrm{Mg}=24,\mathrm{P}=31,\mathrm{C}=12,\mathrm{H}=1$ )

A 10 g effervescent tablet containing sodium bicarbonate and oxalic acid releases 25 mL of ${\mathrm{CO}}_2$ at $\mathrm{T}=298.15\mathrm{K}$ and $\mathrm{p}=1$ bar. If molar volume of ${\mathrm{CO}}_2$ is 25.0 L under such condition, what is the percentage of sodium bicarbonat …

25 g of an unknown hydrocarbon upon burning produces 88 g of ${\mathrm{CO}}_2$ and 9 g of ${\mathrm{H}}_2\mathrm{O}$. This unknown hydrocarbon contains.

8 g of NaOH is dissolved in 18 g of ${\mathrm{H}}_2\mathrm{O}$. Mole fraction of NaOH in solution and molality (in $\mathrm{mol}{\mathrm{kg}}^{-1}$) of the solution respectively are :

What would be the molality of $20\%$ (mass/mass) aqueous solution of KI ? (molar mass of KI $=166\mathrm{g}{\mathrm{mol}}^{-1}$)

For the following reaction the mass of water produced from 445 g of ${\mathrm{C}}_{57}{\mathrm{H}}_{110}{\mathrm{O}}_6$ is …

A solution of sodium sulphate contains 92 g of ${\mathrm{Na}}^{+}$ ions per kilogram of water. The Molality of ${\mathrm{Na}}^{+}$ ions in that solution in $\mathrm{mol}{\mathrm{kg}}^{-1}$ is

At 300 K and 1 atmospheric pressure, 10 mL of a hydrocarbon required 55 mL of ${\mathrm{O}}_2$ for complete combustion, and 40 mL of ${\mathrm{CO}}_2$ is formed. The formula of the hydrocarbon is:

The ratio of mass percent of C and H of an organic compound $\left({\mathrm{C}}_{\mathrm{X}}{\mathrm{H}}_{\mathrm{Y}}{\mathrm{O}}_{\mathrm{Z}}\right)$ is $6:1$. If one molecule of the above compound ( ${\mathrm{C}}_{\mathrm{X}}{\mathrm{H}}_{\mathrm{Y}}{\mathrm{O}}_{\mathrm{Z}}$ ) …

1 gram of a carbonate $({\mathrm{M}}_2{\mathrm{CO}}_3)$ on treatment with excess HCl produces 0.01186 mole of ${\mathrm{CO}}_2$. The molar mass of ${\mathrm{M}}_2{\mathrm{CO}}_3$ in $\mathrm{g}{\mathrm{mol}}^{-1}$ is :