The s-Block Elements Test 42

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The s-Block Elements Test 42

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Weekly Quiz Competition

Question 1
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The correct order of increase thermal stability of $${K_2}C{O_{3,}}MgC{O_{3,}}CaC{O_3}$$ and $$BeC{O_3}$$ is

A
$$BeC{O_3} < MgC{O_3} < {K_2}C{O_3} < CaC{O_3}$$

B
$$BeC{O_3} < MgC{O_3} < {Ca}C{O_3} < {K_2}C{O_3}$$

C
$$MgC{O_3} < BeC{O_3} < CaC{O_3} < {K_2}C{O_3} $$

D
$${K_2}C{O_3} < MgC{O_3} < CaC{O_3} < BeC{O_3} $$

Solution

As the size of cation increases the bond between cation and carbonate ion ($$CO_3^{-2}$$) becomes weak so the thermal stability decreases.

So the correct order of thermal stability is :$$BeCO_3<MgCO_3<CaCO_3<K_2CO_3$$.

Hence option C is correct.
Question 2
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Which one of the following species dose not exist under normal conditions?

A
$$Li_2$$

B
$${ Be }_{ 2 }^{ + }$$

C
$$Be_2$$

D
$$B_2$$

Solution
Question 3
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Directions For Questions

The properties of lithium and beryllium and their compounds differ far from those of the other group 1 and 2 elements and compounds.
Lithium compounds may show closer similarities towards group 2 elements (particularly Mg) than they show towards their own group.
Similarly Be is also closer to Al.

...view full instructions

Which type of salt is formed by only Li of group I ?

A
Nitrate salt

B
Nitride salt

C
Nitrite salt

D
Carbonate salt

Solution
Question 4
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Which one of the alkali metals,forms only,the normal oxide $$M_2O$$ on heating in air?

A
$$Li$$

B
$$Na$$

C
$$Rb$$

D
$$K$$

Solution
Question 5
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The melting point of lithium (181$$^\circ$$C) is just double the melting point of sodium (98$$^\circ$$C) because

A
down the group, the hydration energy decreases

B
down the group, the ionization energy decreases

C
down the group, the cohesive energy decreases

D
None of these

Solution
Question 6
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Which of the following forms complex ions readily ?

A
$$B{e^{2 + }}$$

B
$$M{g^{2 + }}$$

C
$$S{r^{2 + }}$$

D
$$B{a^{2 + }}$$
Question 7
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Which one of the following statements is correct regarding s-block element?

A
Superoxides of alkali metals are black in colour.

B
$$CsI$$ (Cesium iodide) is less soluble in water due to high covalent character.

C
On heating $${\text{LiN}}{{\text{O}}_{\text{3}}}$$ gives a brown gas.

D
Oxide and hydroxide of $${\text{Be}}$$ are acidic in nature.
Question 8
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Which of the following is not true regarding beryllium?

A
It is not readily attacked by acids.

B
Its chloride may have bridge structure in vapour phase.

C
Its hydride is electron-deficient and polymeric in nature.

D
It burns brilliantly in powdered form to give beryllium peroxide.
Question 9
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Which of the following statements is false ?

A
$${\text{M}}{{\text{g}}^{{\text{2 + }}}}$$ ion form a complex with ATP

B
$${\text{C}}{{\text{a}}^{{\text{2 + }}}}$$ on are important in blood clotting

C
$${\text{C}}{{\text{a}}^{{\text{2 + }}}}$$ ion are not important in maintaining the regular beating of the heart.

D
$${\text{M}}{{\text{g}}^{{\text{2 + }}}}$$ ion are important in the green parts of plants.

Solution
Question 10
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Which of the following relation is correct?

A
$$TiC>ScN>MgO>NaF$$ (Hardness)

B
$$NaCl<CsCl$$ (Lattice energy)

C
$$BeCl_{ 2 }>{ MgCl }_{ 2 }>{ CaCl }_{ 2 }$$ ( Melting point )

D
None of these