List of top Chemistry Questions

Identify the correct answer
What do you observe on pouring potassium hydroxide on red and blue litmus papers?
The uncertainty in the determination of the position of a small ball of mass 10 g is \(10^{-33}\) m. With what \% of accuracy can its speed be measured, if it has a speed of 52.5 m s\(^{-1}\)?
At 25°C and 1 atm pressure, the enthalpy of combustion of benzene (l) and acetylene (g) are \(3268 \, \text{kJ mol}^{-1}\) and \(1300 \, \text{kJ mol}^{-1}\), respectively. The change in enthalpy for the reaction 
the enthalpyis
Salicylaldehyde is synthesized from phenol, when reacted with

A hydrocarbon containing C and H has 92.3% C. When 39 g of hydrocarbon was completely burnt in O2, x moles of water and y moles of CO2 were formed. x moles of water is sufficient to liberate 0.75 moles of H2 with Na metal. What is the weight (in g) of oxygen consumed?

1 gram of sodium hydroxide was treated with 25 ml. of 0.75 M HCI solution, the mass of sodium hydroxide left unreacted is equal to
At 300 K, the vapour pressure of toluene and benzene are 3.63 kPa and 9.7 kPa, respectively. What is the composition of vapour in equilibrium with the solution containing 0.4 mole fraction of toluene?
The Enthalpy of combustion of C$_6$H$_6$COOH(s) at 25$^\circ$C and 1.0 atm pressure is -2546 kJ/mol. What is the Internal energy change for this reaction?
What is the quantity of current required to liberate 16g of O\(_2\) (g) during electrolysis of water? (Given 1F = 96500C)
At 300 K, 6 g of urea was dissolved in 500 mL of water. What is the osmotic pressure (in atm) of the resultant solution? (R = 0.082 L atm K$^{-1}$ mol$^{-1}$) (C=12;N=14;O=16;H=1)
Oxidation number of H in NaH, CaH$_2$, and LiH, respectively is:
Match List I with List II.
List I
(Molecule)		List II
(Number and types of bond/s between two carbon atoms)
A.ethaneI.one σ-bond and two π-bonds
B.etheneII.two π-bonds
C.carbon molecule, C2III.one σ-bonds
D.ethyneIV.one σ-bond and one π-bond
Choose the correct answer from the options given below:
The Henry’s law constant (KH) values of three gases (A, B, C) in water are 145, 2 × 10–5 and 35 kbar, respectively. The solubility of these gases in water follow the order :
Activation energy of any chemical reaction can be calculated if one knows the value of
In which of the following processes entropy increases?
A. A liquid evaporates to vapour.
B. Temperature of a crystalline solid lowered from 130 K to 0 K.
C. 2NaHCO3(s) → Na2CO3(s)+CO2(g)+H2O(g)
D. Cl2(g) → 2Cl(g)
Choose the correct answer from the options given below:
The E° value for the Mn3+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to change of
Fehling’s solution ‘A’ is
On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as
Match List I with List II

List-I
(Reaction)

List-II 
(Reagents/Condition)

(A)
Match Reaction with the correct Reagents/Condition
(I)Match Reaction with the correct Reagents/Condition
(B)Match Reaction with the correct Reagents/Condition(II)CrO3
(C)Match Reaction with the correct Reagents/Condition(III)KMnO4/KOH, \(\Delta\)
(D)Match Reaction with the correct Reagents/Condition(IV)(i) O3
(ii) Zn-H2O

Choose the correct answer from the options given below:
Mass in grams of copper deposited by passing 9.6487 A current through a voltmeter containing copper sulphate solution for 100 seconds is (Given : Molar mass of Cu : 63 g mol–1 , 1 F = 96487 C)
For given reaction: 
Reaction
‘P’ is
The products A and B obtained in the following reactions, respectively, are
3ROH+PCI3→3RCI+A 
ROH+PCI5→RCI+HCI+B
The rate of a reaction quadruples when temperature changes from 27°c to 57°c. Calculate the energy of activation
Given R=8.314 J K-1 mol-1, log 4=0.6021
During the preparation of Mohr’s salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of Fe2+ ion?