The s-Block Elements Test 35

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The s-Block Elements Test 35

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Weekly Quiz Competition

Question 1
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Which of the following is/are correct statement(s)?

A
$$Ca_3(PO_4)_2$$ in part of bones

B
$$3Ca_3(PO_4).CaF_2$$ is part of enamel on teeth

C
$$Ca^{2+}$$ ions are important in blood clotting

D
All of the above are correct

Solution

Calcium ions are essential for the formation of bones and teeth, the enamel in theteeth is a double salt of calcium, $$3Ca_3(PO_4)_2 .CaF_2$$.
The organic parts of the bone contain several proteins and $$Ca_3(PO_4)_2$$.
In body, Calcium ions are involved in blood clotting, normal muscle contraction.
Question 2
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Directions For Questions

Question given below are based on the above shown values of hydration energy and lattice energy:

...view full instructions

Hydration energy
$${\Delta H}_{hydra}.(kJ \,mol^{-1})$$ Lattice energy
$${\Delta H_u}(kJ \,mol^{-1})$$
$$Li^+$$ -499 LiCl-840
$$Na^+$$-390 NaCl-776
$$K^+$$-305 KCl-703
$$Cl^-$$-382
Which salt can be used to control humidity?

A
$$LiCl$$

B
$$NaCl$$

C
$$KCl$$

D
None of these

Solution

$$\Delta\,H_{solution}\, =\, \Delta\,H_{hydration}\, -\, \Delta\,H_{lattice\ energy}$$

$$\Delta H_{Hydration}\, =\, \Delta H_{hydration}(cation)\, +\, \Delta H_{hydration} (anion)$$

$$\Delta\,H_{solution}$$ $$(LiCl) = -499 -382 + 840 = -41\ kJ/mol$$
Similarly,
$$\Delta\,H_{solution} (NaCl) = -4 kJ/mol $$
$$\Delta\,H_{solution} (KCl) = +16 kJ/mol $$

As $$\Delta\,H_{solution} (LiCl)$$ is highest so it will absorb water most easily and it can control humidity easily.
Question 3
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Burning of Mg is extinguished by :

A
throwing $$N_2$$ liquid

B
throwing sand

C
throwing ice

D
throwing water

Solution

Magnesium fires cannot be extinguished by water. Magnesium continues to burn after oxygen is depleted. It than reacts with nitrogen from air to form magnesium nitride $$(Mg_3N_2)$$. When attempts are made to extinguish magnesium fires with water, magnesium aggressively reacts with hydrogen gas.
Question 4
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The first ionization potentials ($$eV$$) of $$Be$$ and $$B$$ respectively are:

A
$$8.29, 9.32$$

B
$$9.32, 9.32$$

C
$$8.29, 8,29$$

D
$$9.32,8.29$$

Solution

The first ionization potentials ($$eV$$) of $$Be$$ and $$B$$ respectively are $$9.32, 8,29$$.

According to theory as we move from lest to right in a period the ionization potential should increase but in case of $$Be$$ and $$B$$ Beryllium is having more ionization potential than Boran due to completely filled s orbital in Beryllium($$1s^{2}2s^{2}$$).

Hence option D is correct.
Question 5
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In the mineral, barium ion can be identified by :

A
green colour in ame

B
yellow precipitate with $$Cr{ O }_{ 4 }^{ 2- }$$solution

C
white precipitate with $$S{ O }_{ 4 }^{ 2- }$$

D
all of the above

Solution

$${ Ba }^{ 2+ }$$ ion in solution produces a yellow precipitate with $$K_{2}CrO_{4}$$
$$Ba^{2+} + k_{2}CrO_{4}\rightarrow BaCrO_{4}\downarrow + 2K^+$$

$${ Ba }^{ 2+ }$$ ions in solution produces a white precipitate with $$(NH_4)_2SO_{4}$$ Solutions.
$${ Ba }^{ 2+ }+(NH_4)_2SO_4\rightarrow \underset{White\, ppt}{BaSO_4 \downarrow}+2NH_{4}^+$$

Hence option- (D) is correct.
Question 6
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The hydration energy of $$Mg^{2+}$$ is greater than that of :

A
$$A1^{3+}$$

B
$$Na^{+}$$

C
$$Be^{3+}$$

D
$$Mg^{3+}$$

Solution

$$Mg^{2+}$$ has the larger hydration energy, because hydration energy increases with the charge on the cation and decreases as the size of the cation increases. Therefore answer is $$Na^+$$.
Question 7
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The alkali metal that reacts with nitrogen directly to form nitride is:

A
$$Li$$

B
$$Na$$

C
$$K$$

D
$$Rb$$

Solution

Alkali metals that react with nitrogen directly to form nitride is $$Li$$. This anamolous behaviour is due to its small size and high polarizing power.
$$6 Li + N_2(g)\rightarrow 2 Li_3N$$
Hence, option A is correct.
Question 8
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Out of the elements marked A, B, C, D, E, F, G and H
which form super oxide?

A
E and G

B
C, E and G

C
A and D

D
G and B

Solution

As we move from top to bottom in a group the tendency of formation of superoxides will be increased due to an increase in the atomic size of the elements
As we move from left to right in a period the tendency of formation of superoxides will be decreased due to a decrease in the atomic size of the elements.
So elements E and G forms super oxides.
Hence option A is correct.
Question 9
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The product obtained on fusion of $$BaS{ O }_{ 4 }$$ and $${ Na }_{ 2 }C{ O }_{ 3 }$$ is:

A
$$BaC{ O }_{ 3 }$$

B
$$BaO$$

C
$$Ba{ \left( OH \right) }_{ 2 }$$

D
$$BaHS{ O }_{ 4 }$$

Solution

When $$BaS{ O }_{ 4 }$$ and $${ Na }_{ 2 }C{ O }_{ 3 }$$ are fused, $$BaC{ O }_{ 3 }$$ is obtained.
$$BaSO_4+Na_2CO_3\rightarrow BaCO_3+2NaSO_4$$
Question 10
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Which of the following is not a alkali metal?

A
sodium

B
potassium

C
gold

D
lithium

Solution

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Hydration energy $${\Delta H}_{hydra}.(kJ \,mol^{-1})$$	Lattice energy $${\Delta H_u}(kJ \,mol^{-1})$$
$$Li^+$$ -499	LiCl-840
$$Na^+$$-390	NaCl-776
$$K^+$$-305	KCl-703
$$Cl^-$$-382

The s-Block Elements Test 35

Result

The s-Block Elements Test 35

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SHARING IS CARING

Question 1

$$Ca_3(PO_4)_2$$ in part of bones

$$3Ca_3(PO_4).CaF_2$$ is part of enamel on teeth

$$Ca^{2+}$$ ions are important in blood clotting

All of the above are correct

Solution

Question 2

$$LiCl$$

$$NaCl$$

$$KCl$$

None of these

Solution

Question 3

throwing $$N_2$$ liquid

throwing sand

throwing ice

throwing water

Solution

Question 4

$$8.29, 9.32$$

$$9.32, 9.32$$

$$8.29, 8,29$$

$$9.32,8.29$$

Solution

Question 5

green colour in ame

yellow precipitate with $$Cr{ O }_{ 4 }^{ 2- }$$solution

white precipitate with $$S{ O }_{ 4 }^{ 2- }$$

all of the above

Solution

Question 6

$$A1^{3+}$$

$$Na^{+}$$

$$Be^{3+}$$

$$Mg^{3+}$$

Solution

Question 7

$$Li$$

$$Na$$

$$K$$

$$Rb$$

Solution

Question 8

E and G

C, E and G

A and D

G and B

Solution

Question 9

$$BaC{ O }_{ 3 }$$

$$BaO$$

$$Ba{ \left( OH \right) }_{ 2 }$$

$$BaHS{ O }_{ 4 }$$

Solution

Question 10

sodium

potassium

gold

lithium

Solution

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