List of top Chemistry Questions

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.

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

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

The copper (II) halide which does not exist is

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

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.

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

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?

Which of the following are carbonate ores? l) Magnetite II) Kaolinite III) Siderite IV) Calamine

Which one of the following has maximum number of hybrid orbitals ?

Observe the following molecules. $PCl_5, BrF_5, ClF_5, PF_5, ClF_3, XeF_4, XeF_2, IF_5 $ The number of molecules having square pyramidal geometry from the above is

Noble metals like gold and platinum are soluble in which of the following mixtures?

Acetic acid on heating with $ {NH_3}$ forms $A$. When $A$ reacts with $ {LiAlH_4}$ followed by hydrolysis gives $B$. When $B$ is heated with chloroform in $KOH$ medium gives $C$. What are $B$ and $C$ respectively?

$KO _{2}$, reacts with water to form $A, B$ and $C .$ $B$ forms $C$ when it reacts with iodine in basic medium. What are $B$ and $C$ respectively?

Which of the following is water-gas shift reaction?

White phosphorus is heated with concentrated $NaOH$ in $CO _{2}$ atmosphere to form a gas $A$ and compound $B$. When $A$ is bubbled into aqueous $CuSO _{4}$ solution copper phosphide and $C$ are formed, $B$ and $C$ are respectively

Which one of the following is not present in the nitration mixture?

$KMnO _{4}$ oxidises $S _{2} O _{3}^{2-}$ to $SO _{4}^{2-}$ in medium $x$ and $NO^{-}_2$ to $NO^{-}_3$ in medium $y, x$ and $y$ are respectively

The walls of a closed cubical box of edge $60\, cm$ are made of material of thickness $1\, mm$ and thermal conductivity $4 \times 10^{-4} \; cal \; s^{-1} \; cm^{-1} {^{\circ}C^{-1}}$. The interior of the box is maintained $1000 \; {^{\circ}C}$ above the outside temperature by a heater placed inside the box and connected across $400\, V\, DC$ supply. The resistance of the heater is

Which of the following reactions can be used to prepare diborane? I) $ {BF_3 + LiAlH_4 ->[ether]}$ II) $ {BF_3 + NaH ->[450 k]}$ III) $ {Na_2B_4O_7 + H_2O -> }$ IV) $ { NaBH_4 + I_2 ->}$

Which of the following metals exist in liquid state duiing summer season?

Which of the following orders are correct against the property given? I) dipole moment : $NF_3 > NH_3 >BF_3$ II) Covalent bond length : $C - O > N - O > O - H$ III) Bond order : $C_2 > B_2 > He_2$

The reaction in which $\Delta H > \Delta U$ is