Some Basic Concepts of Chemistry

The incorrect postulates of the Dalton's atomic theory are:

(A) Atoms of different elements differ in mass.

(B) Matter consists of divisible atoms.

(C) Compounds are formed when atoms of different element combine in a fixed ratio.

(D) All the atoms of given element have different properties including mass.

(E) Chemical reactions involve reorganisation of atoms.

Choose the correct answer from the options given below:

An organic compound has 42.1% carbon, 6.4% hydrogen and remainder is oxygen. If its molecular weight is 342, then its molecular formula is:

7.3 g of benzalacetone is synthesized from 10.6 g of benzaldehyde using acetone as another reactant. Percentage yield of benzalacetone is (memory based jee mains shift-2 29/01/2025)

Choose the Incorrect Statement about Dalton's Atomic Theory

[JEE Main 2024, 4 Apr (Shift 2)]

The correct name of I & II in the following process is :

Solid \(\overset{\mathrm{I}}{\to }\)Vapours\(\overset{\mathrm{II}}{\to }\)Solid
Memory Based Question 28/Jan/25 Evening shift

Choose the Incorrect Statement about Dalton's Atomic Theory

The quantity which changes with temperature is:

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 \(0^\circ C\) are possible in Celsius scale, but in Kelvin scale negative temperature is not possible.
(E) Precision refers to the closeness of various measurements for the same quantity.

Choose the correct answer from the options given below

Which of the following mixing of 1 M base and 1 M acid leads to the largest increase in temperature?

[JEE Main 2025, 24 Jan (Shift 2)]

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 g/mL.

[JEE Main 2025, 28 Jan (Shift 1)]

Given below are two statements.

Statement-I: One mole of propyne reacts with excess of sodium to liberate half a mole of hydrogen gas.

Statement-II: Four grams of propyne reacts with sodium amide to liberate ammonia gas which occupies 224 mL at STP.

In the light of above statements, choose most appropriate answer from options given below

[JEE Main 2025, 22 Jan (Shift 1)]

7.3 g of benzalacetone is synthesized from 10.6 g of benzaldehyde using acetone as another reactant. Percentage yield of benzalacetone is (memory based jee mains shift-2 29/01/2025)

The number of moles of methane required to produce 11g CO₂(g) after complete combustion is:

(Given molar mass of methane in g mol^–1 : 16)

Find the value of solubility of zirconium phosphate with formula \(\left[{\mathrm{Zr}}_{3}{\left({\mathrm{PO}}_{4}\right)}_{4}\right]\) in terms of solubility product Ksp

0.1 M solution of KI reacts with excess of \({H}_{2}S{O}_{4}\) and \(KI{O}_{3}\) solutions. According to equation

\(5{I}^{-}+I{O}_{3}^{-}+6{H}^{+}\to 3{I}_{2}+3{H}_{2}O\)

Identify the correct statements :
(A) 200 mL of KI solution reacts with 0.004 mol of \(KI{O}_{3}\)
(B) 200 mL of KI solution reacts with 0.006 mol of \({H}_{2}S{O}_{4}\)
(C) 0.5 L of KI solution produced 0.005 mol of \({I}_{2}\)
(D) Equivalent weight of \(KI{O}_{3}\) is equal to (\(\frac{\text{ Molecular weight }}{5}\))

Choose the correct answer from the options given below

\(2.8\times {10}^{-3}\mathrm{mol}\mathrm{of}{\mathrm{CO}}_{2}\)is left after removing \({10}^{21}\)molecules from its ' x ' mg sample. The mass of \({\mathrm{CO}}_{2}\) taken initially is

(Given : \({\mathrm{N}}_{\mathrm{A}}=6.02\times {10}^{23}{\mathrm{mol}}^{-1}\))

[JEE Main 2025, 23 Jan (Shift 1)]

Density of 3 M NaCl solution is 1.25 g/mL. The molality of the solution is

In a compound contains 54.2 % carbon, 9.2 % of hydrogen and rest are oxygen. What is molecular formula of compound, if molecular mass is 132 g/mol ?
(Memory Based JEE Mains 24/01/2025 ,Shift -2)

Which of the following sets of quantum numbers have the same energy?

(a) n=2 , l=2 , m=+1

(b) n=2 , l=1 , m=-1

(c) n=3, l=2 , m=0

(d) n=3 , l=2 , m=1

Which of the following is an example of a heterogeneous substance?

The correct option for the mass of \(\mathrm{CO}_2\) produced by heating \(20 \mathrm{~g}\) of \(20 \%\) pure limestone is
(Atomic mass of \(\mathrm{Ca}=40\)u)
\(\left[{\mathrm{CaCO}}_{3}\overset{1200\mathrm{K}}{\to }\mathrm{CaO}+{\mathrm{CO}}_{2}\right]\)