Potassium dichromate belongs to which crystal system?

• Tetragonal

• Orthorhombic

• Triclinic

• Hexagonal

Which one of the following is an incorrect statement?

• O₃ oxidises PbS to PbSO4

• O₃ oxidises nitric oxide to nitrogen dioxide

• O₃ oxidises aqueous Kl at pH = 9.2

• The two oxygen-oxygen bond lengths in O₃ are different

In Solvay process of manufacture of sodium carbonate, the by-product is

• NH₄Cl

• NaHCO₃

• CaCl₂

• CO₂

Among the following compounds, the one that gets hydrolysed to form metallic hydroxide, hydrogen peroxide and oxygen is

• Na₂O

• Na₂O₂

• Li₂O

• KO₂

The alkaline earth metal with the least density value is

• Mg

• Be

• Sr

• Ca

Be and Al exhibit diagonal relationship. Which of the following statements about them is/ are not true?

I. Both react with HCl to liberate H2

II. They are made passive by HNO₃

Ill. Their carbides give acetylene on treatment with water

IV. Their oxides are amphoteric

• III only

• III and IV

• I and III

• I only

Which one of the following on hydrolysis, gives the corresponding metallic hydroxide, H₂O₂ and O₂?

• Li₂O

• Na₂O₂

• NaO₂

• Na₂O

The metal that produces red-violet colour in the non-luminous flame is

• Ba

• Ag

• Rb

• Pb

249.

Which pair of the following chlorides do not impart colour to the flame?

• BeCl₂ and SrCl₂

• BeCl₂ and MgCl₂

• CaCl₂ and BaCl₂

• BaCl₂ and SrCl₂

Sodium peroxide which is a yellow solid, when exposed to air becomes white due to the formation of

• H₂O₂

• NaOH and Na₂CO₃

• Na₂O

• NaOH and H₂O₂