List of top Chemistry Questions asked in UP Board XII

On Cannizzaro’s reaction formaldehyde forms:

The rate constant of a reaction A + 2B $\longrightarrow$ Product is expressed by the equation $R = [A][B]^2$. The molecularity of reaction will be:

69.77% Carbon, 11.63% Hydrogen and the rest Oxygen is present in an organic compound. The molecular mass of the compound is 86. The compound does not reduce Tollen’s reagent but gives an addition compound with sodium hydrogen sulphite and gives positive iodoform test. On strong oxidation it gives ethanoic acid and propanoic acid. Write the structure of possible compound.

R–NH$_2$ + CHCl$_3$ + 3KOH (alc.) $\longrightarrow$ RNC + 3KCl + 3H$_2$O. The above reaction is:

How many moles of water are present in 180 g of water?

An aromatic organic compound A on treatment with aqueous ammonia and heating forms compound B, which on heating with Br$_2$ and KOH forms a compound C of molecular formula C$_6$H$_7$N. Write the structures and names of compounds A, B and C.

How will you convert chlorobenzene into the following? (Write chemical equations only) (i) Benzene
(ii) Phenol
(iii) Toluene
(iv) Aniline
(v) Diphenyl

For the reaction 2A + B $\longrightarrow$ 2C + 3D, the rate of change in concentration of C is 1.0 mol L$^{-1$ s$^{-1}$. Find the rate of reaction and rate of change in concentration of A, B and D.}

A reaction is of first order with respect to a reactant. How is the rate of reaction affected, if the concentration of the reactant is doubled?

Write short notes on: (i) Williamson’s ether synthesis
(ii) Fermentation
(iii) To obtain methyl alcohol from pyroligneous acid

What happens when (Write chemical equations only): (i) \textit{n}-Butyl chloride reacts with alcoholic KOH?
(ii) Bromobenzene reacts with magnesium in the presence of dry ether?
(iii) Ethyl chloride reacts with aqueous KOH?
(iv) Methyl bromide reacts with sodium in the presence of dry ether?
(v) Ethyl bromide reacts with KCN (alc.)?

For the reaction $N_2O_5 \longrightarrow 2NO_2 + \tfrac{1{2}O_2$, if} \[ -\frac{d[N_2O_5]}{dt} = K'[N_2O_5], \quad \frac{d[NO_2]}{dt} = K''[N_2O_5], \quad \frac{d[O_2]}{dt} = K'''[N_2O_5] \] then establish the relation between $K'$, $K''$, and $K'''$.

An aromatic organic compound A yields B and C when it reacts with CHCl$_3$ and KOH. On distillation with Zn dust, D is formed. On oxidation, D yields compound E having molecular formula C$_7$H$_6$O$_2$. Identify A, B, C, D and E. Write the chemical equation of each reaction also.

In the reaction 2A $\longrightarrow$ Products, concentration of A decreases from 0.5 mol L$^{-1$ to 0.4 mol L$^{-1}$ in 10 minutes. Find the rate of reaction during the time interval.}

Classify each of the following solids as ionic, metallic and molecular: P$_4$, Ammonium phosphate, Brass, Tetraphosphorus decoxide (P$_4$O$_{10}$), Rb, I$_2$, LiBr

Ketones do not reduce Fehling’s solution and Tollen’s reagent, while fructose containing ketonic group does. Why?

Describe Ostwald’s process for the manufacture of nitric acid. How will you detect NO$_3^-$ radical in this acid? Give equations for reactions involved.

Answer the following: (i) How do the atomic radii of transition metals vary across a series and why?
(ii) Ions of transition metals are generally paramagnetic. Why?
(iii) Transition elements show different oxidation states. Why?

Using IUPAC norms, write the systematic names of the following: (i) [Co(NH$_3$)$_6$]Cl$_3$
(ii) K$_3$[Cr(C$_2$O$_4$)$_3$]
(iii) [Pt(NH$_3$)$_2$Cl$_2$]
(iv) [Ni(CO)$_4$]

Prove the presence of five –OH groups and a –CHO group in glucose molecule, giving chemical equations. How is silver mirror formed from glucose?

Differentiate between molar and molal elevation constants. Give two different formulae involving these two constants for the determination of molecular mass of solute.

Explain with reason: (i) The colloidal solution of Fe(OH)$_3$ obtained from FeCl$_3$ is positively charged.
(ii) Alum is used for the purification of water.
(iii) Rivers form a delta while joining a sea/ocean.

Amino acids are structural units of:

Give any two dehydrating properties of H$_2$SO$_4$.

1 : 1 Molar mixture of FeSO$_4$ and (NH$_4$)$_2$SO$_4$ gives test of Fe$^{2+$ ions, but 1 : 4 molar mixture of CuSO$_4$ and NH$_3$ (aq) does not give test of Cu$^{2+}$ ions. Why?}