Some Basic Concepts of Chemistry — JEE Main PYQs

80 mL of a hydrocarbon on mixing with 264 mL of oxygen in a closed U-tube undergoes complete combustion. The residual gases after cooling to 273 K occupy 224 mL. When the system is treated with KOH solution, the volume decreases to 64 mL. The formula of the hydrocarbon is:

14.0 g of calcium metal is allowed to react with excess HCl at 1.0 atm pressure and 273 K.
Which of the following statements is incorrect?
[Given: Molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}$ of $\mathrm{Ca}-40,\mathrm{Cl}-35.5,\mathrm{H}-1$]

In the reaction,
$2\mathrm{Al}(\mathrm{s})+6\mathrm{HCl}(\mathrm{aq})\to 2{\mathrm{Al}}^{3+}(\mathrm{aq})+6{\mathrm{Cl}}^{-}(\mathrm{aq})+3{\mathrm{H}}_2(\mathrm{g})$

By usual analysis, 1.00 g of compound (X) gave 1.79 g of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is: (nearest integer)
(Given, molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}$: O=16, Mg=24, P=31)

At $\mathrm{T}(\mathrm{K}),100\mathrm{g}$ of $98\%{\mathrm{H}}_2{\mathrm{SO}}_4(\mathrm{w}/\mathrm{w})$ aqueous solution is mixed with 100 g of $49\%{\mathrm{H}}_2{\mathrm{SO}}_4(\mathrm{w}/\mathrm{w})$ aqueous solution. What is the mole fraction of …

$\mathrm{A}+2\mathrm{B}⟶{\mathrm{AB}}_2$

36.0 g of 'A' (Molar mass : $60\mathrm{g}{\mathrm{mol}}^{-1}$ ) and 56.0 g of ' B ' (Molar mass : $80\mathrm{g}{\mathrm{mol}}^{-1}$ ) are allowed to react. Which of the following statements are correct?
(A) ' A …

The mass of benzanilide obtained from the benzoylation reaction of 5.8 g of aniline, if yield of product is 82%, is _____ g (nearest integer).
(Given molar mass in ${\mathrm{g}\mathrm{mol}}^{-1}$ H: 1, C: 12, N: 14, O: 16)

A student has planned to prepare acetanilide from aniline using acetic anhydride. The student has started from 9.3 g of aniline. However, the student has managed to obtain 11 g of dry acetanilide.
The % yield of this reaction is :-

0.53 g of an organic compound (x) when heated with excess of nitric acid (concentrated) and then with silver nitrate gave 0.75 g of silver bromide precipitate. 1.0 g of (x) gave 1.32 g of $\mathrm{CO}{}_2$ gas on combustion. The percentage of hydrogen in the compound (x) is ______ %. [N …

For the given reaction;
${\mathrm{CaCO}}_3+2\mathrm{HCl}\to {\mathrm{CaCl}}_2+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$
If $90\mathrm{g}{\mathrm{CaCO}}_3$ is added to 300 mL of HCl which contains $38.55\%$ HCl by mass and has density …

The mass of iron converted into ${\mathrm{Fe}}_3{\mathrm{O}}_4$ by the action of 18 g of steam is :
(Given : Molar mass of H, O and Fe are 1, 16 and $56\mathrm{g}{\mathrm{mol}}^{-1}$ respectively)

Assume iron is present in excess :

One mole of an alkane (x) requires 8 mole oxygen for complete combustion. Sum of number of carbon and hydrogen atoms in the alkane (x) is $\_\_\_\_$.

Number of moles and number of molecules in 1.4187 L of $\mathrm{SO}{}_2$ at STP respectively are

The ratio of mass percentage (w/w) of C:H in a hydrocarbon is 12:1. It has two carbon atoms. The weight (in g) of $\mathrm{CO}{}_2$(g) formed when 3.38 g of this hydrocarbon is completely burnt in oxygen is:
(Given: Molar mass in ${\mathrm{g}\mathrm{mol}}^{-1}$ C: 12, H: 1, O: 16)

Complete combustion of X g of an organic compound gave 0.25 g of $\mathrm{CO}{}_2$ and 0.12 g of $\mathrm{H}{}_2\mathrm{O}$. If the % of carbon is 25% and of hydrogen is 4.89%, then X = _____ $\times 10^{-3}$ g. (Nearest integer)
(Molar mass of C, H and O are 12, 1 and 16 ${\mathrm{g}\mathrm{mol}}^{-1}$ respecti …

The correct order of total number of atoms of present in
(A) 2 moles of cyclohexane
(B) 684 g of sucrose
(C) 90.8 L of dihydrogen at STP

How many grams of residue is obtained by heating 2.76 g of silver carbonate?
(Given : Molar mass of $\mathrm{C},\mathrm{O}$ and Ag are 12, 16 and $108\mathrm{g}{\mathrm{mol}}^{-1}$ respectively)

What is the mole fraction of water in $10\%$ by weight $(\mathrm{w}/\mathrm{w})$ of aqueous urea solution ?
[Given : Molar mass of H, O, C and N are 1, 16, 12 and $14\mathrm{g}{\mathrm{mol}}^{-1}$ respectively]

What volume of hydrogen gas at STP would be liberated by action of 50 mL of ${\mathrm{H}}_2{\mathrm{SO}}_4$ of $50\%$ purity (density $=1.3\mathrm{g}{\mathrm{mL}}^{-1}$ ) on 20 g of zinc?

Given : Molar mass of H, O, S, Zn are 1, 16, 32, 65 …

An oxide of iron contains $69.9\%$ iron, its empirical formula, is :
(Given : Molar mass of Fe and O are 56 and $16\mathrm{g}{\mathrm{mol}}^{-1}$ respectively.)

Which of the following contain the same number of atoms?
(Given : Molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}$ of $\mathrm{H},\mathrm{He},\mathrm{O}$ and S are $1,4,16$ and 32 respectively)
A. 2 g of ${\mathrm{O}}_2$ gas
B. 4 g fo ${\mathrm{SO}}_2$ gas
C. 1400 mL of …

Match List-I (Mass of substance) with List-II (Number of atoms). [N_A = Avogadro number]

Some ${\mathrm{CO}}_2$ gas was kept in a sealed container at a pressure of 1 atm and at 273 K . This entire amount of ${\mathrm{CO}}_2$ gas was later passed through an aqueous solution of $\mathrm{Ca}(\mathrm{OH}{)}_2$. The excess unreacted $\mathrm{Ca}(\mathrm{OH}{)}_2$ …

Density of 3 M NaCl solution is $1.25\mathrm{g}/\mathrm{mL}$. The molality of the solution is :

20 mL of 2 M NaOH solution is added to 400 mL of 0.5 M NaOH solution. The final concentration of the solution is ____ $\times 10^{-2}$ M. (Nearest integer).

Xg of benzoic acid on reaction with aq. ${\mathrm{NaHCO}}_3$ release ${\mathrm{CO}}_2$ that occupied 11.2 L volume at STP. X is ____ g.

Consider the following reaction occurring in the blast furnace.
${\mathrm{Fe}}_3{\mathrm{O}}_{4(\mathrm{s})}+4{\mathrm{CO}}_{(\mathrm{g})}\to 3{\mathrm{Fe}}_{(\mathrm{l})}+4{\mathrm{CO}}_{2(\mathrm{g})}$
' $x$ ' kg of iron is produced when …

The elemental composition of a compound is $54.2\%,\mathrm{C},9.2\%\mathrm{H}$ and $36.6\%\mathrm{O}$. If the molar mass of the compound is $132\mathrm{g}{\mathrm{mol}}^{-1}$, the molecular formula of the compound is :
[Given : The relative atomic mass of …

The hydrocarbon $(\mathrm{X})$ with molar mass $80\mathrm{g}{\mathrm{mol}}^{-1}$ and $90\%$ carbon has ____ degree of unsaturation.

$2.8\times 10^{-3}\mathrm{mol}$ of ${\mathrm{CO}}_2$ is left after removing $10^{21}$ molecules from its ' x ' mg sample. The mass of ${\mathrm{CO}}_2$ taken initially is
Given: ${\mathrm{N}}_{\mathrm{A}}=6.02\times 10^{23}{\mathrm{mol}}^{-1}$

Quantitative analysis of an organic compound (X) shows following % composition.

C : 14.5%
Cl : 64.46%
H : 1.8%
(Empirical formula mass of the compound $(\mathrm{X})$ is
_____ $\times 10^{-1}$
(Given molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}$ of …

The molarity of a $70\%$ (mass/mass) aqueous solution of a monobasic acid ( X ) is _____ M(Nearest integer)
[Given : Density of aqueous solution of ( X ) is $1.25\mathrm{g}{\mathrm{mL}}^{-1}$

Molar mass of the acid is $70\mathrm{g}{\mathrm{mol}}^{-1}$ ]

0.01 mole of an organic compound (X) containing $10\%$ hydrogen, on complete combustion produced $0.9\mathrm{g}{\mathrm{H}}_2\mathrm{O}$. Molar mass of (X) is ______ $\mathrm{g}{\mathrm{mol}}^{-1}$.

When 81.0 g of aluminium is allowed to react with 128.0 g of oxygen gas, the mass of aluminium oxide produced in grams is ______. (Nearest integer)
Given :
Molar mass of Al is $27.0\mathrm{g}{\mathrm{mol}}^{-1}$
Molar mass of O is $16.0\mathrm{g}{\mathrm{mol}}^{-1}$

Concentrated nitric acid is labelled as $75\%$ by mass. The volume in mL of the solution which contains 30 g of nitric acid is ____ .
Given : Density of nitric acid solution is $1.25\mathrm{g}/\mathrm{mL}$

Choose the correct statements.
(A) Weight of a substance is the amount of matter present in it.
(B) Mass is the force exerted by gravity on an object.
(C) Volume is the amount of space occupied by a substance.
(D) Temperatures below $0^{\circ }\mathrm{C}$ are possible in Celsiu …

0.1 mole of compound 'S' will weigh ______ g.
(Given molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}$ C: 12, H: 1, O: 16)

$\mathrm{CaCO}{}_3(\mathrm{s})+2\mathrm{HCl}(\mathrm{aq})\to \mathrm{CaCl}{}_2(\mathrm{aq})+\mathrm{CO}{}_2(\mathrm{g})+\mathrm{H}{}_2\mathrm{O}(\mathrm{l})$
Consider the above reaction, what mass of $\mathrm{CaCl}{}_2$ will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of $\mathrm{CaCO}{}_3$?
(Given : Molar mass of Ca, C, O, H and Cl are 40, 12, 16, 1 and 35.5 g mol${}^{-1}$, respectiv …

On complete combustion 1.0 g of an organic compound (X) gave 1.46 g of ${\mathrm{CO}}_2$ and 0.567 g of ${\mathrm{H}}_2\mathrm{O}$. The empirical formula mass of compound (X) is ______ g.
(Given molar mass in …

$0.1\mathrm{mol}$ of the following given antiviral compound $(\mathrm{P})$ will weigh ______ $\times 10^{-1}\mathrm{g}$

(Given : molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}\mathrm{H}:1,\mathrm{C}:12,\mathrm{N}:14$, O : 16, F : 19, I : 127)

Among $10^{-9}\mathrm{g}$ (each) of the following elements, which one will have the highest number of atoms?

Element : Pb, Po, Pr and Pt

0.5 g of an organic compound on combustion gave 1.46 g of ${\mathrm{CO}}_2$ and 0.9 g of ${\mathrm{H}}_2\mathrm{O}$. The percentage of carbon in the compound is _____. (Nearest integer)
[Given : Molar mass (in $\mathrm{g}{\mathrm{mol}}^{-1}$ ) C: 12, H: 1, O : 16]

Sea water, which can be considered as a 6 molar (6 M) solution of NaCl, has a density of $2{\mathrm{g}\mathrm{mL}}^{-1}$. The concentration of dissolved oxygen (${\mathrm{O}}_2$) in sea water is 5.8 ppm. Then the concentration of dissolved oxygen (${\mathrm{O}}_2$) in sea water, is …

The amount of calcium oxide produced on heating 150 kg limestone (75% pure) is ______ kg.
(Nearest integer)
Given: Molar mass (in ${\mathrm{g}\mathrm{mol}}^{-1}$) of Ca-40, O-16, C-12

Fortification of food with iron is done using FeSO₄·7H₂O. The mass in grams of the FeSO₄·7H₂O required to achieve 12 ppm of iron in 150 kg of wheat is ____ (Nearest integer)
[Given: Molar mass of Fe, S and O respectively are 56, 32 and 16 g mol⁻¹]

Butane reacts with oxygen to produce carbon dioxide and water following the equation given below
${\mathrm{C}}_4{\mathrm{H}}_{10}(\mathrm{g})+\frac{13}{2}{\mathrm{O}}_2(\mathrm{g})\to 4{\mathrm{CO}}_2(\mathrm{g})+5{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$
If 174.0 kg o …

An organic compound weighing 500 mg , produced 220 mg of ${\mathrm{CO}}_2$. on complete combustion. The percentage composition of carbon in the compound is ______ %. (nearest integer)
(Given molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}$ of $\mathrm{C}:12,\mathrm{O}:16$ )

Thyroxine, the hormone has given below structure

The percentage of iodine in thyroxine is ______ %.
(nearest integer)
(Given molar mass in $\mathrm{g}{\mathrm{mol}}^{-1}\mathrm{C}:12.\mathrm{H}:1,\mathrm{O}:16$, N:14, I:127)

On combustion 0.210 g of an orgainc compound containing C , H and O gave 0.127 g H₂O and 0.307 g CO₂. The percentages of hydrogen and oxygen in the given organic compound respectively are:

20 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is _____ M. (Nearest Integer value)
(Given: Na=23, I=127, Ag=108, N=14, O=16 g mol⁻¹)