List of top Chemistry Questions

The volume of 2 moles of an ideal gas at STP is:

Define the following terms:
(i) Mole fraction
(ii) Molality
(iii) Molarity
(iv) Mass percentage.

An ideal gas undergoes an isothermal process at 300 K. If the initial volume is 2 m$^3$ and it doubles to 4 m$^3$, what is the work done by the gas? (Take $R = 8.31 \, \text{J/(mol.K)}$, and assume 1 mole of gas.)

Calculate the empirical formula of a compound containing 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass.

What is the molarity of a solution prepared by dissolving 5 moles of solute in 2 liters of solution?

How many moles are there in 18 grams of water ($ \text{H}_2\text{O} $)? (Atomic masses: H = 1, O = 16)

For the reaction $N_2(g) + 3H_2(g) \rightleftharpoons 2\text{NH}_3(g)$ at 298 K, the enthalpy change $ \Delta H = -92.4 \, \text{kJ/mol} $. What happens to the equilibrium when temperature is increased?

Calculate the volume occupied by 4.4 g of CO$_2$ gas at 27°C and 1 atm pressure. ($ R = 0.0821 \, \text{L-atm/mol-K} $, Molar mass of CO$_2$ = 44 g/mol)

For a first-order reaction, the rate constant $ k $ is $ 1.386 \times 10^{-3} \, \text{s}^{-1} $. What is the half-life $ t_{1/2} $ of the reaction? (Use $ \ln 2 = 0.693 $)

Calculate the molality of a solution prepared by dissolving 10 g of NaCl ($ M = 58.5 \, \text{g/mol} $) in 500 g of water:

In a redox titration, 25 mL of 0.1 M KMnO$_4$ is required to completely react with oxalic acid in acidic medium. The volume of 0.2 M oxalic acid used is:
(Balanced reaction: $ 2\text{MnO}_4^- + 5\text{C}_2\text{O}_4^{2-} + 16\text{H}^+ \rightarrow 2\text{Mn}^{2+} + 10\text{CO}_2 + 8\text{H}_2\text{O} $)

What is the molarity of a solution prepared by dissolving 4 g of NaOH in 250 mL of solution? (Molar mass of NaOH = 40 g/mol)

The enthalpy change for the reaction
$2H_2(g) + O_2(g) → 2H_2O(l)$
is -572 kJ/mol. What is the enthalpy change for the formation of 1 mole of $H_2O(l)$}?

Which of the following is the IUPAC name for $CH_3CH_2CH_2OH$?

What is the hybridization of the central atom in $NH_3$?

Vapour pressure of water at 293 K is 17.535 mm Hg. Calculate the vapour pressure of water at 293 K when 25 g of glucose is dissolved in 450 g of water.

The mass of 60% HCl by mass required for the neutralisation of 10 L of 0.1 M NaOH is

Write the Nernst equation and emf of the following cells at 298 K :
(i) Mg(s) | Mg²⁺ (0.001M) || Cu²⁺(0.0001 M) | Cu(s)
(ii) Fe(s) | Fe²⁺ (0.001M) || H⁺ (1M)|H₂(g)(1bar) | Pt(s)
(iii) Sn(s) | Sn²⁺(0.050 M) || H⁺ (0.020 M) | H₂(g) (1 bar) | Pt(s)
(iv) Pt(s) | Br₂(l) | Br^- (0.010 M) || H⁺ (0.030 M) | H₂(g) (1 bar) | Pt(s).

Draw all the isomers (geometrical and optical) of:
(i) $[CoCl_2(en)_2]^{+}$
(ii)$ [Co(NH_3)Cl(en)_2] ^{2+} $
(iii)$ [Co(NH_3)_2Cl_2(en)]^{+}$

$0.833$ mole of a carbohydrate with empirical formula $CH_{2}O$ , has $10\, g$ of hydrogen. Molecular formula of the carbohydrate is

Define the term solution. How many types of solutions are formed? Write briefly about each type with an example.

For the reaction,

{C O}_{(g)} + {C l}_{2 (g)} ⇌ {C O C l}_{2 (g)}

, then

K_{p} / K_{c}

is equal to:

How would you account for the following:

Of the d⁴ species, Cr²⁺ is strongly reducing while manganese(III) is strongly oxidising.
Cobalt(II) is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised.
The d¹ configuration is very unstable in ions.

Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

Which of the following is/are endothermic reaction(s)?