Periodic Table & Periodicity — Page 16 | JEE Chemistry

Q151

What are the products formed in sequence when excess of CO2 is passed in slaked lime?

A Ca(HCO3)2, CaCO3

B CaCO3, Ca(HCO3)2

C CaO, Ca(HCO3)2

D CaO, CaCO3

Correct Answer

Option B

Solution

Ca{(OH)_2} + C{O_2} \to CaC{O_3} \downarrow + {H_2}O

CaC{O_3} \downarrow + C{O_2} + {H_2}O \to Ca{(HC{O_3})_2}

Q152

Choose the correct statement from the following :

A The standard enthalpy of formation for alkali metal bromides becomes less negative on descending the group.

B The low solubility of CsI in water is due to its high lattice enthalpy.

C Among the alkali metal halides, LiF is least soluble in water.

D LiF has least negative standard enthalpy of formation among alkali metal fluorides.

Correct Answer

Option C

Solution

a.

Standard enthalpy of formation for alkali metal bromides becomes more negative on descending down the group. b.

In case of CsI, lattice energy is less, but Cs+ is having less hydration enthalpy due to which it is less soluble in water. c.

For alkali metal fluorides, the solubility in water increases from lithium to caesium.

LiF is least soluble in water. d.

Standard enthalpy of formation for LiF is most negative among alkali metal fluorides.

Q153

The major component/ingredient of Portland Cement is :

A tricalcium aluminate

B tricalcium silicate

C dicalcium aluminate

D dicalcium silicate

Correct Answer

Option B

Solution

Major component of Portland cement is "Tricalcium silicate (51%, 3CaO.SiO2)

Q154

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Lithium salts are hydrated. Reason (R) : Lithium has higher polarising power than other alkali metal group members. In the light of the above statements, choose the most appropriate answer from the options given below :

A Both (A) and (R) are correct but (R) is not the correct explanation of (A)

B (A) is correct but (R) is not correct.

C (A) is not correct but (R) is correct.

D Both (A) and (R) are correct and (R) is the correct explanation of (A)

Correct Answer

Option A

Solution

Lithium salts are hydrated due to high hydration energy of Li+ Li+ due to smallest size in IA group has highest polarizing power.

Q155

Amongst baking soda, caustic soda and washing soda, carbonate anion is present in :

A washing soda only.

B washing soda and caustic soda only.

C washing soda and baking soda only.

D baking soda, caustic soda and washing soda.

Correct Answer

Option A

Solution

Baking soda $\to$ NaHCO3 Washing soda $\to$ Na2CO3.10H2O Caustic soda $\to$ NaOH

\text{CO}^{-2}_{3}

ion is present only in washing soda.

Q156

Addition of H2SO4 to BaO2 produces :

A BaO, SO2 and H2O

B BaHSO4 and O2

C BaSO4, H2 and O2

D BaSO4 and H2O2

Correct Answer

Option D

Solution

\mathrm{BaO}_{2} \cdot 8 \mathrm{H}_{2} \mathrm{O}+\mathrm{H}_{2} \mathrm{SO}_{4} \rightarrow \mathrm{BaSO}_{4}+\mathrm{H}_{2} \mathrm{O}_{2}+\mathrm{H}_{2} \mathrm{O}

This is a common method to prepare hydrogenperoxide

Q157

BeCl2 reacts with LiAlH4 to give :

A Be + Li[AlCl4] + H2

B Be + AlH3 + LiCl + HCl

C BeH2 + LiCl + AlCl3

D BeH2 + Li[AlCl4]

Correct Answer

Option C

Solution

2BeCl2 + LiAlH4 $\to$ 2 BeH2 + LiCl + AlCl3 The above reaction using LiAlH4 is an important preparation method for production of hydrides.

Q158

The correct order of melting point is :

A Be > Mg > Ca > Sr

B Sr > Ca > Mg > Be

C Be > Ca > Mg > Sr

D Be > Ca > Sr > Mg

Correct Answer

Option D

Solution

\begin{array}{ll}\text{Element } & \text{ M.P. } \\ \mathrm{Be} & 1560 \mathrm{~K} \\ \mathrm{Mg} & 924 \mathrm{~K} \\ \mathrm{Ca} & 1124 \mathrm{~K} \\ \mathrm{Sr} & 1062 \, \text{K}\end{array}

Q159

s-block element which cannot be qualitatively confirmed by the flame test is :

A Li

B Na

C Rb

D Be

Correct Answer

Option D

Solution

Beryllium does not give flame test because of its small size and high ionization energy the energy of flame is not sufficient to excite the electrons to higher energy level.

Q160

Which one of the following alkaline earth metal ions has the highest ionic mobility in its aqueous solution?

A Be2+

B Mg2+

C Ca2+

D Sr2+

Correct Answer

Option D

Solution

In aqueous solution, the ionic mobility is inversely proportional to the charge density on the ion.

Hence Sr2+ has highest ionic mobility in water.