Tag: the s-block elements

Questions Related to the s-block elements

Which of the following represents the use(s) of Sorel's cement?

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

  1. It is used as a dental stopping

  2. It is used as finish for plaster

  3. It is used for cementing glass and metal together

  4. All of the above

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Correct Option: D
Explanation:

The following represents the use(s) of Sorel's cement.

  1. It sets to a hard white mass. Hence, it is used as a dental stopping.
  2. It takes a very good polish and is used as a finish for plaster.
  3. It is used for cementing glass and metal together.

When burned in open air, the magnesium gets hot enough to produce noticeable amounts of yellow magnesium nitride. Burning in a covered crucible that allows enough air in to support combustion will reduce the burning temperature, thus maximizing the production of the nitride.

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

  1. True

  2. False

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Correct Option: B
Explanation:

When magnesium burns, it is actually reacting with oxygen in the air and not with fire. Fire is what we call the heat and light produced when things burn Magnesium reacts with oxygen to make a compound called magnesium oxide. The bright light results because this reaction produces a lot of heat. so given statement is false

Magnesium oxide is produced by the calcination of magnesium phosphate or magnesium sulphate by the treating magnesium chloride with lime followed by heat.

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

  1. True

  2. False

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Correct Option: B
Explanation:

It is produced by the calcination of magnesium carbonate or magnesium hydroxide.The latter is obtained by the treatment of magnesium chloride solutions, typically seawater, with lime.

How can Calcium Suphate be produced from Calcium Fluoride?

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

  1. ${CaF} _{2}$ ${+}$ ${H} _{2}{SO} _{4}$

  2. ${CaF} _{2}$ ${+}$ ${SO} _{2}$

  3. $CaF _2 + H _2S$

  4. None of these

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Correct Option: A
Explanation:

Calcium Fluoride is treated with Sulphuric Acid to give Hydrogen Fluoride and a precipitate of Calcium Sulphate. The balanced equation can be written as-
${CaF} _{2}$ ${+}$ ${H} _{2}{SO} _{4}$ ${=}$ ${2HF}$ ${+}$ ${CaSO} _{4}$

Which of the following statement about magnesium oxide is/are correct?

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

  1. It is a relatively poor desiccant

  2. The largest consumer of magnesia is refractory industry

  3. It is used for making Portland cement

  4. In medicine, magnesium oxide is used for relief of heartburn and sour stomatch

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Correct Option: A,B,C,D

Magnesium on heating in air gives $(A)$ and $(B)$. On reaction with water $(B)$ gives colourless gas $(C)$. $(C)$ when passed through $CuSO _4$ solution gives a blue coloured solution $(D)$. The blue solution is:

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

  1. $MgO$

  2. $Mg _3N _2SO _3.H _2O$

  3. $NH _3$

  4. $[Cu(NH _3) _4]SO _4.H _2O$

Show answer
Correct Option: D
Explanation:

Option $(D)$ is correct.

Magnesium on strong heating reacts with nitrogen of air.
$Mg + O _2 \rightarrow MgO  [A] + Mg _3N _2 [B]$
$Mg _3N _2 [B]  + H _2O \rightarrow Mg(OH) _2 + NH _3 [C]$
$ NH _3 + CuSO _4(aq) \rightarrow [Cu(NH _3) _4]SO _4.H _2O [D]$

$MgO$ when mixed with a saturated solution of $MgCl _2$ sets to a hard mass known as 'sorel cement'. The composition of sorel cement is $MgCl _2.nMgO.xH _2O$. The value of $n$ is:

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

  1. 2

  2. 5

  3. 3

  4. 1

Show answer
Correct Option: C
Explanation:

There are two types of sorel cement 3 phase and 5 phase.

$MgCl _2.3Mg(OH) _2.8H _2O$ is 3 phase sorel cement.