p-Block Elements

NEET Chemistry · 114 questions · Page 2 of 12 · Click an option or "Show Solution" to reveal answer

Q11

HCl was passed through A solution of CaCl 2 , MgCl 2 and NaCl. Which of the following compound(s) crystallize(s)?

A Only NaCl

B Only MgCl 2

C NaCl, MgCl 2 and CaCl 2

D Both MgCl 2 and CaCl 2

Correct Answer

Option A

Solution

Since CaCl 2 and MgCl 2 are more soluble than NaCl, on passing HCl(g) through A solution containing CaCl 2 , MgCl 2 and NaCl, then NaCl crystallizes out (common ion effect).

Q12

Which of the following is an amphoteric hydroxide?

A Mg(OH) 2

B Be(OH) 2

C Sr(OH) 2

D Ca(OH) 2

Correct Answer

Option B

Solution

Be(OH) 2 is an amphoteric hydroxide as it reacts with acid as well as base while others are basic hydroxide.

Be(OH) 2 + 2HCl $\to$ BeCl 2 + 2H 2 O Be(OH) 2 + 2NaOH $\to$ Na 2 [Be(OH) 4 ]

Q13

Enzymes that utilize ATP is phosphate transfer require an alkaline earth metal (M) as the cofactor. M is

A Ca

B Sr

C Be

D Mg

Correct Answer

Option D

Solution

Mg is acts as a cofactor for all the enzymes involved in ATP phosphate transfer.

Q14

Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is 1s 2 2s 2 2p 3 , the simplest formula for this compound is

A Mg 2 X 3

B MgX 2

C Mg 2 X

D Mg 3 X 2

Correct Answer

Option D

Solution

Electronic configuration of element (X) is 1s 2 2s 2 2p 3 So, valency of X will be 3.

Since, valency of Mg is 2.

So, formula of compound formed by Mg and X will be Mg 3 X 2 .

Q15

Among CaH 2 , BeH 2 , BaH 2 , the order of ionic character is

A BeH 2 < CaH 2 < BaH 2

B CaH 2 < BeH 2 < BaH 2

C BeH 2 < BaH 2 < CaH 2

D BaH 2 < BeH 2 < CaH 2

Correct Answer

Option A

Solution

Smaller the size of cation, more will be its polarising power. Hence BeH2 will be least ionic. BeH 2 < CaH 2 < BaH 2

Q16

Ionic mobility of which of the following alkali metal ions is lowest when aqueous solution of their salts are put under an electric field?

A K

B Rb

C Li

D Na

Correct Answer

Option C

Solution

Li + being smallest, has maximum charge density.

So, Li + is most heavily hydrated among all alkali metal ions.

Effective size of Li + in aqueous solution is therefore, largest.

So, moves slowest under electric field.

Q17

In context with beryllium, which one of the following statements is incorrect?

A It is rendered passive by nitric acid.

B It forms Be 2 C

C Its salts rarely hydrolyze.

D Its hydride is electron-deficient and polymeric.

Correct Answer

Option C

Solution

Beryllium salts are readily hydrolysed.

Q18

The suspension of slaked lime in water is known as

A lime water

B quick lime

C milk of lime

D aqueous solution of slaked lime.

Correct Answer

Option C

Solution

This process is known as slaking of lime.

The paste of lime in water (suspension) is called milk of lime while the filtered and clear solution is known as lime water.

Q19

The product obtained as a result of a reaction of nitrogen with CaC 2 is

A CaCN 2

B Ca 2 CN

C Ca(CN) 2

D CaCN

Correct Answer

Option A

Solution

CaC 2 + N 2 $\to$ CaCN 2 + C

Q20

Which of the following statments is false?

A Ca 2+ ions are not important in maintaining the regular beating of the heart.

B Mg 2+ ions are important in the green parts of the plants.

C Mg 2+ ions form a complex with ATP.

D Ca 2+ ions are important in blood clotting.

Correct Answer

Option A

Solution

Ca 2+ ions are required to trigger the contraction of muscles and to maintain the regular beating of the heart.

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