Tag: chemistry

Questions Related to chemistry

Which of the following represents carnalite?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $MgCl _2$ (anhydrous)

  2. $ KCl \cdot MgCl _2$ (anhydrous)

  3. $ KCl \cdot MgCl _2 \cdot 6H _2O$

  4. $ MgCl _2 \cdot 6H _2O$

Show answer
Correct Option: C
Explanation:

$ KCl \cdot MgCl _2 \cdot 6H _2O$ represents carnalite.

$ MgCl _2 \cdot 6H _2O$ is obtained from carnalite. Which of the following is true?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $ MgCl _2 \cdot 6H _2O$ is left behind in the fused mass

  2. $ MgCl _2 \cdot 6H _2O$ solidifies when fused mass is cooled to 176 deg C

  3. $KCl$ remains in the fused state

  4. Solvent extraction is used to extract $KCl$

Show answer
Correct Option: A
Explanation:

Carnalite ($ KCl \cdot MgCl _2 \cdot 6H _2O$) is fused and cooled to 176 deg C.  Potassium content solidifies and $ MgCl _2 \cdot 6H _2O$ remains infused state. Fused mass is separated from deposited $KCl$ and is allowed to cool. The remaining $KCl$ is separated by deposition of carnalite crystals, which crystallizes out first.
$ MgCl _2 \cdot 6H _2O$ is left behind in the fused mass.

Which of the following is obtained when magnesium chloride reacts with calcium hydroxide?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $Mg(OH) _2$

  2. $Mg$

  3. $Ca$

  4. $CaO$

Show answer
Correct Option: A
Explanation:

When magnesium chloride reacts with calcium hydroxide, $Mg(OH) _2$ and $ CaCl _2(aq) $ are obtained.
$MgCl _2(aq) + Ca(OH) _2(aq) \rightarrow  Mg(OH) _2(s) + CaCl _2(aq) $

Which the correct chemical reaction among following?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $MgSO _4 \xrightarrow {\Delta} MgO+SO _3$

  2. $Mg _NO _2 \rightarrow Mg _3+N _2$

  3. $MgCO _3 \rightarrow Mg+ CO+CO _2$

  4. $Mg+H _2O \rightarrow Mg(OH) _2+H _2$

Show answer
Correct Option: A
Explanation:

Option $(A)$ is correct.

A). $MgSO _4 \xrightarrow {\Delta} MgO+SO _3$
C). $MgCO _3 \rightarrow Mg + CO _2$
D). $Mg+H _2O \rightarrow MgO + H _2$.
Magnesium reacts with water vapor to magnesium hydroxide and hydrogen gas

Reaction of magnesium with air is:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. endothermic reaction

  2. reversible reaction

  3. exothermic reaction

  4. substitution reaction

Show answer
Correct Option: C
Explanation:

Option $(C)$ is correct.

The reaction of magnesium with air is an exothermic reaction as magnesium burns with dazzling brilliance in the air forming white shiny magnesium oxide with the evolution of a lot of heat.
$2Mg + O _2 \rightarrow 2MgO + heat$

If magnesium is gently heated, it forms:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. magnesium oxide

  2. magnesium sulfide

  3. magnesium nitrite

  4. magnesium carbonate

Show answer
Correct Option: A
Explanation:

Option $(A)$ is correct.

If magnesium is gently heated, it forms magnesium oxide with the release of a large amount of heat.
$2Mg + O _2 \rightarrow 2MgO + heat$

Oxide used to treat indigestion and relieve pain is:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. magnesium oxide

  2. magnesium hydroxide

  3. potassium oxide

  4. both $A$ and $B$

Show answer
Correct Option: D
Explanation:

Option $(D)$ is correct.

Oxide used to treat indigestion and relieve pain are magnesium oxide and magnesium hydroxide.
They act as an antacid to relieve indigestion, sour stomach, and heartburn.

Color of solid magnesium is:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. dark grey

  2. silvery grey

  3. black

  4. whitish silver

Show answer
Correct Option: B
Explanation:

Option $(B)$ is correct.

The colour of solid magnesium is silvery grey. It has a shiny lustre, also known as a glow. When it burns, magnesium creates a white light. 

Which of the following statement is correct?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. Magnesium oxide is highly soluble in water

  2. Magnesium oxide is slightly solution in water

  3. Magnesium oxide is insoluble in water

  4. All alkaline earth metal oxides are insoluble in water

Show answer
Correct Option: B
Explanation:

Option $(B)$ is correct.

Magnesium oxide is slightly soluble in water.It is due to an intramolecular force of the magnesium oxide compound. In fact, magnesium oxide is very small, and the attraction forces are very strong to be broke apart when reacted with water.

Color of magnesium oxide is:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. white

  2. blue

  3. grey

  4. pink

Show answer
Correct Option: A
Explanation:

Option $(A)$ is correct.

Color of magnesium oxide is white. It is hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium.