CBSE 11TH CHEMISTRY - Online Test
Q1. Boron forms only covalent compounds and not +3 ions because
Answer : Option C
Explaination / Solution:
Due to smaller size and high nuclear charge B has very high ionization energy value so does not show +3 oxidation state.
Further according to Fajan's rule, cation with small size and high positive charge leads to covalent bond.
Q2. One of the following p-block elements has unusually low melting point
Answer : Option B
Explaination / Solution:
Ga does not do not follow any of the simple crystal structures. And two nearest Ga atoms are bonded by covalent bond which leads to low melting point.
Q3. Which of the following p-block elements in group 13 could exist in liquid state during summer
Answer : Option C
Explaination / Solution:
Ga has very low melting point (MP = 29.76oC), and because of that it can exists in liquid state during summer.
Q4. The relative stability of +1 oxidation state progressively increases for heavier elements. Choose one of the following haing most stable +1 oxidation state.
Answer : Option B
Explaination / Solution:
Due to inert pair effect Tl+1 (G-2) is most stable oxidation state.
Q5. Aluminium when exposed to air protects itself from further attack by
Answer : Option B
Explaination / Solution:
Al forms a thick layer of oxide (Al2O3) on its surface which protects it from further attack.
Q6. White fumes appear around the bottle of anhydrous aluminium chloride.Why?
Answer : Option C
Explaination / Solution:
White fumes appears because of formation of HCl on reaction with atmospheric moisture.
White fumes appears due to the formation of HCl gas. Anhydrous aluminium chloride is partly hydrolyzed by the moisture in the atmosphere and produces HCl gas. This HCl further combines with the moisture of the air and appears white fumes.
AlCl3 +3H2O --> Al(OH)3 +3HCl
Q7. Diborane is produced on an industrial scale by the reaction of BF3 with
Answer : Option D
Explaination / Solution:
Reaction of BF3 with NaH produces B2H6 At 450K following reaction happens
2BF3 + 6NaH --> B2H6 + 6NaF
Q8.
The angular shape of ozone molecules () consists of
Answer : Option B
Explaination / Solution:
consists of 2 sigma bond and 1 pie bond.
Q9. Argon is used
Answer : Option B
Explaination / Solution:
Argon is noble gas. Ar is used in high temp welding to provide inert atmosphere.
Q10. Silicon is the second most abundant element on the earth’s crust and is a component of
Answer : Option A
Explaination / Solution:
Si is the most imp component of ceramics, which is comprised of metal, non-metal, or metalloids held by ionic or covalent bond.
