List of top Chemistry Questions

Purine bases present in $DNA$ are adenine and guanine. The base thymine is present in $RNA$ while base uracil is present in $DNA$.

$pK_a$ value of phenol is $10.0$ while that of ethanol is $15.9$ Ethanol is stronger acid than phenol.

$ PHBV$ is a biodegradable polymer. $ PHBV$ is an aliphatic polyester.

Oxidation state of oxygen in $OF_{2}$ and $Na_{2}O$ is $+2$ and $-2$ respectively. Oxygen is an electronegative element.

$O_{2}$ molecule is diamagnetic while $C_{2}$ molecule is paramagnetic in nature. Bond order of $O_ 2$ molecule is $1.5$ and that of $C_2$ molecule is $2.5$.

$Na_{2}O$ is basic oxide whereas $Cl_{2}O_{7}$ is acidic oxide. Elements on extreme left form basic oxides whereas elements on extreme right form acidic oxides.

Lyophilic colloids have a unique property of protecting lyophobic colloids. Lyophilic colloids are extensively solvated.

Lithium salts are mostly hydrated. The hydration enthalpies of alkali metal ions decrease with increase in ionic sizes.

$K_4[Fe(CN)_6]$ is diamagnetic and $[Fe(H_2O)_6 ]Cl_3$ is paramagnetic. Hybridisation of central metal m $K_4[Fe(CN)_6] is \,sp^3d^2,$ while in $[Fe(H_2O)_6]Cl_3\, is\, d^2\, sp^3$

Isocyanide test can be used to distinguish between secondary and tertiary amines. Tertiary amines on heating with chloroform and ale. $KOH$ form foul smelling substances.

In the series $Sc$ to $Zn$, the enthalpy of atomisation of zinc is the lowest. Zinc has greater number of unpaired electrons.

In vapour state sulphur is paramagnetic in nature. In vapour state sulphur exists as $S_2$ molecule.

In the metallury of aluminium, purified $Al_2O_3$ is mixed with $Na_3AlF_6$ or $CaF_2$. $Na_3AlF_6$ or $CaF_2$ lowers the melting point of mixture and increases its conductivity.

In the presence of alkaline $KMnO_{4} 4-$ methylacetophenone is oxidised to benzoic acid. Keto group is oxidised to $??OOH$ group.

In the reaction, $2Cu_{2}O_{\left(s\right)}+Cu_{2}S_{\left(s\right)} \rightarrow 6 Cu_{\left(s\right)}+SO_{2\left(g\right)}$ copper acts as a reductant and sulphur acts as an oxidant. The given reaction is not a redox reaction.

In Rutherford?? $\alpha$ -particle scattering experiment, most of the $\alpha$ -particles were deflected by nearly $180^{\circ}$. The positive charge of the atom is spread throughout the atom that repelled and deflected the positively charged $\alpha$-particles.

In $NH_3, N$ is $sp^3$ hybridised but bond angle is $107^{\circ}$. Shape of $NH_{3}$ molecule is trigonal pyramidal.

In hydrogen and hydrogen like species, orbital energy depends only on the quantum number $n$ whereas in multi-electron atoms it depends on quantum numbers $n$ and $I$. The principal quantum number determines the size and the energy of the orbital.

In crystalline solids, the value of resistance is different in different directions. Crystalline solids are isotropic in nature.

Hydrolysis of ester is an example of auto catalytic reaction. A catalyst speeds up the process without participating in the mechanism.

Hofmann degradation of benzamide gives aniline. Hofmann bromamide degradation reaction can be used for descending amine series.

$HNO_{2}$ can act both as a reducing agent and an oxidising agent. In $HNO_{2},$ oxidation state of nitrogen is $+3 $ which can change from $-3$ to $+5$.

Haloalkanes react with $KCN$ to form alkyl cyanides as main product while with $AgCN$ form isocyanide as the main product. $KCN$ and $AgCN$, both are ionic compounds.

Geometrical isomerism is also called cis-trans isomerism. Tetrahedral complexes show geometrical isomerism.

Glucose gets oxidised to gluconic acid on reaction with mild oxidising agent like bromine water. Glucose contains a keto group.