List of top Chemistry Questions

A copper coin was electroplated with Zn and then heated at high temperature until there is a change in colour. What will be the resulting colour ?

The compound(s), capable of producing achiral compound on heating at 100°C is/are

Average atomic weight of an element M is 51.7. If two isotopes of $M, M^{50}$ and $M^{52}$ are present, then percentage of occurrence of $M^{50}$ in nature will be.

Eutrophication causes

1 L of 2 M CH3COOH is mixed with 1 L of 3M C2H5OH to form an ester. The rate of the reaction with respect to the initial rate when each solution is diluted with an equal volume of water will be

According to the VSEPR theory, the shape of $ClO_3^{-}$ would be

The Crystal Field Stabilisation Energy (CFSE) for $[CoCl_6]^{4-}$ is $18000\, cm^{-1}$. The CFSE for $[CoCl_4]^{2-}$ will be-

Which is the correct thermal stability order for $H_2E$ (E = O. S. Se. Te and $Po$) ?

Which of the following species is not stable ?

Which of the following is incorrect statement ?

The rate of radioactive disintegration at an instant for a radioactive same of half life $2.2 \times 10^9\,s^{-1}$ is $10^{10} \,s^{-1}$. The number of radioactive atoms in that sample at that instant is,

Which will make basic buffer?

A gas at 350 K and 15 bar has molar volume 20 percent smaller than that for an ideal gas under the same conditions. The correct option about the gas and its compressibility factor (Z) is :

The wave functions of $1s$ orbitals of two hydrogen atoms are $\Psi_A$ and $\Psi_B$. $\Psi_A$ and $\Psi_B$ are linearly combined to form two molecular orbitals ($\sigma$ and $\sigma^{\ast}$). Which of the following statements are collect? I. $\sigma^{*}$ is equal to $(\Psi_{A}-\Psi_{B})$. II. In $\sigma$ - orbital, one nodal plane is present in between two nuclei. III. The energy of $\sigma$ - orbital is lower than the energy of $\sigma^{*}$ -orbital.

An organic compound $X\left( C _{7} H _{7} Cl \right)$ when reacted with $KCN / C _{2} H _{5} OH$ gave major product $Y . Z$ is formed when $Y$ is reduced with $LiAlH _{4}$. What are $Y$ and $Z$ ?

Identify $Z$ in the following sequence of reactions. $\ce{ C_2 H_4 Br_2 ->[(i) Alc.KOH][(ii) NaNH_2] X ->[Red\, hot][Fe \,tube\, 873 K] Y ->[(CH_3CO)_2 O/\Delta][Anhyd. AlCl_3] Z}$

Sodium nitrite is reacted with $H_2SO_4$ to form $NaHSO_4, HNO_3$, water and $X$. Gold is dissolved in aqua-regia to form water, $AuCl^{-}_4$ and $Y. X$ and $Y$ are respectively

Chlorine oxidises sulphur dioxide in the presence of water to give an oxyacid $A$. Chlorine also oxidises iodine in the presence of water to give an oxyacid $B$. The oxidation states of $S$ and $I$ in $A$ and $B$ are respectively

$CuSO_4$ solution is electrolysed for $15$ minutes to deposit $0.4725\, g$ of copper at the cathode. The current in amperes requited is (Faraday = $96.500 \,C\,mol^{-1}$. atomic weight of copper = $63$)

The average translational kinetic energy of a molecule in a gas becomes equal to $0.69\, eV$ at a temperature about [Boltzmann constant = $1.38 \times 10^{-23} \; J \; K^{-1}$]

Identify the set of acidic oxides.

In the first order thermal decomposition of $C _{2} H _{5} I (g) \longrightarrow C _{2} H _{4}(g)+ HI (g)$, the reactant in the beginning exerts a pressure of $2$ bar in a closed vessel at $600 \,K$. If the partial pressure of the reactant is $0.1$ bar after $1000$ minutes at the same temperature the rate constant in $\min ^{-1}$ is $(\log 2=0.3010)$

$\ce{H_2C = CH_2 + O_2 ->[Aqueous \; medium] Ch_3CHO}$ What is the catalyst used in the above green reaction?

The copper (II) halide which does not exist is

The pair of metals refined by "vapour phase refining" is