List of top Chemistry Questions

For the complex ion with configurations $d^3$, $d^4$ (low spin), $d^5$ (high spin), $d^7$ (low spin) and $d^6$ (high spin), the total number of unpaired electrons is _ _ _ _ _ _ _ _ _ _ _ _ .

Molar conductivity and conductance of an electrolytic solution are 123.5 Scm$^2$/mole and 0.19 S respectively. Concentration of solution is $x$% w/w, then find the value of x.
(cell constant = 1.3 S cm$^{-1}$; density of solution = 1 gm/ml; molar mass of electrolyte = 75 g/mole)

Silver rod is dipped in aqueous solution of $ \mathrm{AgNO_3} $ of unknown concentration and Zn rod is dipped in $ 1 \, \mathrm{M} $ $ \mathrm{ZnSO_4} $ aqueous solution. Both these containers are connected to form a galvanic cell showing emf of $ 1.6 \, \mathrm{V} $. Calculate the value of $ \log_{10}[\mathrm{Ag}^+] $.
$ E^\circ_{\mathrm{Ag^+/Ag(s)} = 0.8 \, \mathrm{V} \qquad E^\circ_{\mathrm{Zn^{2+}/Zn(s)}} = -0.76 \, \mathrm{V} $
[Use $ \dfrac{2.303RT}{F} = 0.059 $]

For the given reaction:
\[ \mathrm{X_2(g) + Y_2(g) \rightleftharpoons 2XY(g)} \] The following data table is provided at $600 \, \mathrm{K}$:
& $\Delta_f H \, (\mathrm{kJ/mol})$ & $S_m \, (\mathrm{J\,K^{-1}\,mol^{-1}})$
$\mathrm{X_2}$ & 80 & 140
$\mathrm{Y_2}$ & 8 & 250
$\mathrm{XY}$ & 42 & 200
\endtabular Calculate $\Delta_r G$ at $600 \, \mathrm{K}$.

20 g Zn is treated with 50 ml, 50% (w/w) $ \mathrm{H_2SO_4} $ solution $(d = 1.3 \, \mathrm{g/ml})$. The volume of $ \mathrm{H_2} $ gas evolved at STP is:

Determine the order of molar heat capacity $ \left(C_m\right) $ of $ \mathrm{Br_2(\ell) $, $ \mathrm{Cu(s)} $ and $ \mathrm{He(g)} $ at $ 298 \, \mathrm{K} $ and $ 1 \, \mathrm{atm} $.

For the reaction:
\[ \text{A(g)} \rightleftharpoons \text{B(g)} + \text{C(g)} \] Initial moles of A(g) is $a$. At equilibrium, $x$ moles of A decompose at total pressure $P$. Calculate $K_P$ for the given reaction.

In 1 litre aqueous solution 20 g of Haemoglobin is present at 300 K. This solution has height difference of 80 mm, when separated from pure water through S.P.M. If density of solution is 1000 kg/m$^3$, then calculate molar mass of Haemoglobin in kg/mol. (Use : $g = 10$ m/s$^2$)

In a period, ionisation energy of the extreme left and electronegativity of the extreme right element is respectively ______. (Don’t consider Noble gases).

Given below are two statements:

0.2 g of an organic compound is subjected to estimation of $S$ by Carius method, giving $0.6$ g $BaSO_4$. Find \% of $S$. (Nearest integer)

Compare the bond length x, y, and z in the following compound.

The compound

is treated sequentially with: (A) Excess HI/Red P
(B) $ \text{V}_2\text{O}_5 $, 773 K
(C) Benzyl chloride/AlCl$_3$
Find the number of π-bonds in the final product.

Given the nuclear reaction: \[ \text{H}_2^2 + \text{H}_1^2 \rightarrow \text{He}_4 \] Binding energy per nucleon of H$_1^2$ and H$_2^4$ are 1.1 MeV and 7 MeV respectively. Find energy released in the nuclear reaction given above.

The hybridisation states of Ni in the 3 complexes Ni(CO)$_4$, [Ni(NH$_3$)$_6$]$^{2+}$, [Ni(CN)$_4$]$^{2-}$ are

For tetrahedral complex, the correct order of energy of $d$-orbitals is:

Match the following:

Consider the reaction:

Find the number of moles of benzene formed if the efficiency of reaction is 60%.

Sucrose hydrolyses in acidic medium to form glucose and fructose which follows first order kinetics. If the half-life of sucrose is 3 hrs, find the % of sucrose left after 6 hrs.

Select the correct statements : (a) Glucose has 2 anomeric forms.
(b) Both forms have difference in configuration at $C_1$ carbon.
(c) $\alpha$-form has more melting point than $\beta$-form.
(d) Specific rotation of $\alpha$-form is $+19^\circ$ and $\beta$-form has $+112^\circ$.
(e) $\alpha$-form crystallises at $307^\circ$ and $\beta$-form crystallises at $371^\circ$.

Choose the correct match.

(A) Bond angle Cr–O–Cr in $ \text{CrO}_7^{2-} $ is 126° (B) $ \text{Na}_2\text{Cr}_2\text{O}_7 $ is used as primary standard solution in titration. (C) $ \text{K}_2\text{Cr}_2\text{O}_7 $ oxidises $ \text{Fe}^{2+} $ into $ \text{Fe}^{3+} $ in acidic medium. (D) $ \text{CrO}_4^{2-} $ and $ \text{Cr}_2\text{O}_7^{2-} $ are interconvertible by changing pH.

Consider the following reaction:

What is the colour of the final compound B?

Statement-1: Under certain conditions, the covalency of oxygen can be up to 4. In $ \text{SO}_2 $, the oxidation state of oxygen is $ -2 $ and in $ \text{OF}_2 $, the oxidation state of oxygen is $ +2 $. Statement-2: The anomalous behaviour of oxygen in the 16th group is due to its small size and high electronegativity.

Statement-1: Maltose is a non-reducing sugar.

Statement-2: Lactose is a reducing sugar.