List of top Chemistry Questions

Account for the following:
(a) The C–Cl bond length in chlorobenzene is shorter than that in methyl chloride.
(b) Grignard reagents should be prepared under anhydrous conditions.
(c) In case of optically active alkyl halides, S_N1 reactions are accompanied by racemisation.

Arrange the following compounds in the increasing order of their acidic strength:
3,5-dinitrophenol, 4-methylphenol, phenol, 2,4,6-trinitrophenol.

Write an application of reverse osmosis.

For the reaction A + B $\to$ Products, the following initial rates were obtained at various initial concentrations of reactants:

Sl. No.	[A] (mol L-1)	[B] (mol L-1)	Initial rate (mol L-1 s-1)
1	0.1	0.1	0.05
2	0.2	0.1	0.10
3	0.1	0.2	0.05

What is meant by crystal field splitting energy? For a d4 ion, write the configuration if (i) $\Delta_o$<P, and (ii) $\Delta_o$>P.

How does sprinkling of salt help in clearing the snow covered roads in hilly areas?

How can acetaldehyde be prepared from acetyl chloride?

What happens when red blood cells are kept in 0.5\% (mass/vol) NaCl solution? Justify your answer.

Shweta mixed two liquids A and B of 10 mL each. After mixing, the volume of the solution was found to be 20.2 mL.
(i) Why was there a volume change after mixing the liquids?
(ii) Will there be an increase or decrease of temperature after mixing?
(iii) Give one example for this type of solution.

Calculate the elevation of boiling point of a solution when 3 g of CaCl2 (Molar mass = 111 g mol\textsuperscript{-1}) was dissolved in 260 g of water, assuming that CaCl2 undergoes complete dissociation. (Kb for water = 0.52 K kg mol\textsuperscript{-1})

Assertion (A): The boiling points of alkyl halides decrease in the order $R_1>R_3>R_2>R_4$.
Reason (R): The van der Waals forces of attraction decrease in the order $R_1>R_3>R_2>R_4$.

Write the rate law expression for the reaction 2HI → H2 + I2, if the order of the reaction is zero.

Based on the data given above, give plausible reason for the variation of conductivity and molar conductivity with concentration.

Concentration of KCl solution (mol/L)	Conductivity at 298.15 K (S cm-1)	Molar Conductivity at 298.15 K (S cm2 mol-1)
1.000	0.1113	111.3
0.100	0.0129	129.0
0.010	0.00141	141.0

What is the effect of temperature on the rate of reaction? Write a mathematical expression for the same.

Explain the mechanism of acyl catalytic hydrogenation.

CH3CH2CHO and CH3CH2COOH can be distinguished by:

Assertion (A): The solubility of aldehydes and ketones in water decreases with increase in size of the alkyl group.
Reason (R): Aldehydes and ketones have dipole-dipole interaction.

Match the type of cell given in Column I with their use given in Column II.

Column I	Column II
i. Lead storage cell	d. Inverter
ii. Mercury cell	b. Apollo Space Programme
iii. Dry cell	c. Wrist watch
iv. Fuel cell	a. Wall clock

Assertion (A): Henry’s law constant (KH) decreases with increase in temperature.
Reason (R): As the temperature increases, solubility of gases in liquids decreases.

Assertion (A): For measuring resistance of an ionic solution an AC source is used.
Reason (R): Concentration of ionic solution will change if DC source is used.

While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution?

In which of the following groups are both ions coloured in aqueous solution?

Which of the following aldehydes will undergo Cannizzaro reaction?

The treatment of ethyl bromide with alcoholic silver nitrite gives: