If it is assumed that ${}_{92}{}^{235}\mathrm{U}$ decays only by emitting $\mathrm{\alpha }$-and ($\mathrm{\beta }$-particles, the possible product of the decay is

• ${}_{89}{}^{225}\mathrm{Ac}$

• ${}_{89}^{227}\mathrm{Ac}$

• ${}_{89}{}^{230}\mathrm{Ac}$

• ${}_{89}{}^{231}\mathrm{Ac}$

Of the following compounds, the most acidic is

• As₂O₃

• P₂O₅

• Sb₂O₃

• Bi₂O₃

The reaction that takes place when Cl₂ gas is  passed through conc. NaOH solution is

• oxidation

• reduction

• displacement

• disproportionation

14. 'Electron' is an alloy of

• Mg and Zn

• Fe and Mg

• Ni and Zn

• Al and Zn

Blackened oil painting can be restored into original form by the action of

• Cl₂

• BaO₂

• H₂O₂

• MnO₂

Which of the following statements is not correct?

• Silicon is extensively used as a semiconductor

• Carborundum is SiC

• Silicon occurs in free state in nature

• Mica contains the element silicon

The addition of HBr to 2-pentene gives

• 2-bromopentane only

• 3-bromopentane only

• 2-bromopentane and 3-bromopentane

• 1-bromopentane and 3-bromopentane

ethylene can be separated from acetylene by passing the mixture through

• fuming H₂SO₄

• pyrogallol

• ammoniacal Cu₂Cl₂

• charcoal powder

In the compound $\mathrm{HC}\equiv \mathrm{C}-\mathrm{C}\left({\mathrm{CH}}_3\right)={\mathrm{CH}}_2$ the hybridisation of C-2 and C-3 carbons are respectively

• sp³ and sp³

• sp² and sp³

• sp² and sp

• sp³ and sp

The two structures written below represent

• pair of diastereomers

• pair of enantiomers

• same molecule

• both are optically inactive