Which of the following is paramagnetic?

• CO

• N₂

• O₂

• H₂O₂

Yellow phosphorus is kept in

• water

• kerosene

• ether

• alcohol

An element 'Y' emits one $\mathrm{\alpha }$-and two $\mathrm{\beta }$- particles to give 'X'. X and Y are

• isotones

• isobars

• isotopes

• isoelectronics

Which of the following has sp³ -hybridisation?

• BCl₃

• PCl₃

• BeCl₃

• None of these

The pH of 10^-8M NaOH is

• 8.0

• 6.0

• 6.96

• 7.04

For the reaction, 2NO₂ 2NO + O₂, the value of K_p is equal to K. What will the value of K_p for reaction,

NO + $\frac{1}{2}$O₂ $\to$NO₂

• $\sqrt{\mathrm{K}}$

• $\frac{1}{\mathrm{K}}$

• $\sqrt{\frac{1}{\mathrm{K}}}$

• $\frac{1}{{\mathrm{K}}^2}$

Which one of the following elements, is a component of a compound essential for photosynthesis ?

• Iron

• Calcium

• Barium

• Magnesium

The correct order of stability of carbocations, is :

• 1$°$ < 2$°$ < 3$°$ < CH₃

• $\stackrel{+}{\mathrm{C}}$H₃ < 1$°$ < 2$°$ < 3$°$

• 3$°$ < 2$°$ < 1$°$ < $\stackrel{+}{\mathrm{C}}$H₃

• 2$°$ < 3$°$ < 1$°$ < $\stackrel{+}{\mathrm{C}}$H₃

The IUPAC name of the following compound is

• bicyclo [2, 2, 0] octane

• bicyclo [0, 2, 2] hexane

• bicyclo [2, 1, 1] hexane

• bicyclo [2, 2, 0] hexane

20.

The following compound can not exhibit

CH₃CH = CH - CH(OH).COOH

• geometrical isomerism

• optical isomerism

• metamerism

• position isomerism