Tag: some important compounds of magnesium and calcium

Questions Related to some important compounds of magnesium and calcium

Chlorophyll is a ______ complex.

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

  1. Magnesium - Porphyrin

  2. Iron - Porphyrin

  3. Copper - Porphyrin

  4. Nickel - Porphyrin

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Correct Option: A
Explanation:

Chlorophyll is a magnesium - porphyrin complex.
Chlorophyll is the main pigment for the absorption of light in plants and is useful during photosynthesis.

During the manufacturing of single superphosphate, excess silicon combines with acid to form:

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

  1. silicates

  2. silicic acid

  3. silanes

  4. hydride of silicon

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Correct Option: B
Explanation:

The reactions occurring  during the production of superphosphate are complex and are usually summarised as follows :

1. $Ca _5(PO _4) _3 F + 5H _2SO _4 \rightarrow 5CaSO _4 + 3H _3PO _4 + HF$
2. $Ca _5(PO _4) _3F + 7H _3 PO _4 + 5H _2O \rightarrow 5Ca(H _2PO _4) _2 H _2O + HF$
These reactions can be combined to give the overall equation :
$2Ca _5(PO _4) _3F + 7H _2SO _4 + 3 H _2O \rightarrow 7CaSO _4 + 3Ca(H _2PO _4) _2 H _2O + 2HF$
There are other reactions occurring at the same time. For example, virtually all the HF reacts with other silica minerals associated with the fluorapatite (silicates, quartz) to form silicon tetrafluoride. These gaseous emissions are recovered as hydroflusilicic acid $(H _2SiF _6)$ in the scrubbing system. Carbonates in the rock also react with sulfuric acid.

During the manufacturing of single superphosphate, excess silicon combines with:

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

  1. base

  2. acid

  3. water

  4. none

Show answer
Correct Option: B
Explanation:

The reactions occurring  during the production of superphosphate are complex and are usually summarised as follows :

1. $Ca _5(PO _4) _3 F + 5H _2SO _4 \rightarrow 5CaSO _4 + 3H _3PO _4 + HF$
2. $Ca _5(PO _4) _3F + 7H _3 PO _4 + 5H _2O \rightarrow 5Ca(H _2PO _4) _2 H _2O + HF$
These reactions can be combined to give the overall equation :
$2Ca _5(PO _4) _3F + 7H _2SO _4 + 3 H _2O \rightarrow 7CaSO _4 + 3Ca(H _2PO _4) _2 H _2O + 2HF$
There are other reactions occurring at the same time. For example, virtually all the HF reacts with other silica minerals associated with the fluorapatite (silicates, quartz) to form silicon tetrafluoride. These gaseous emissions are recovered as hydroflusilicic acid $(H _2SiF _6)$ in the scrubbing system. Carbonates in the rock also react with sulfuric acid.

During the manufacturing of superphophates, fluorine and silicon impurities combines with water to form:

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

  1. silicic acid

  2. fluorosilicic acid

  3. silicon tetrafluoride

  4. form their oxides

Show answer
Correct Option: B

The impurities present in the phosphate rock is/are:

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

  1. chlorine

  2. fluorine

  3. silicon

  4. carbon

Show answer
Correct Option: B,C
Explanation:

The impurities present in the phosphate rock are silicon and flourine. If phosphate rock is digested in phosphoric acid, silicon dioxide and hydrogen flouride are formed. 

Which of the following is isomorphous with $MgSO _4\cdot 7H _2O$ ?

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

  1. Green vitriol

  2. Blue vitriol

  3. Red vitriol

  4. Vitriol of mass

Show answer
Correct Option: A
Explanation:

Green vitroil is isomorphous with $MgSO _4.7H _2O$

 $MgSO _4.7H _2O$ (epsom salt)
 $FeSO _4.7H _2O$ (green vitriol)
these two are isomorphous .

Which of the following element has $2^{nd} IP<1^{st}IP$?

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

  1. $Mg$

  2. $Na$

  3. $C$

  4. None

Show answer
Correct Option: D
Explanation:

All three $Mg$, $C$ and $Ne$ have $2nd$ ionisation potential greater than $1st$ ionisation potential. 

This is the general trend shown by most element that $1^{st} IP<2^{nd} IP<3^{rd} IP<$ and so on.
Hence, option D is correct.

Gypsum is a widely occurring mineral. It is the sulphate of calcium with two molecules of water attached. On heating it loses three-quarters of its water and becomes:

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

  1. baking soda

  2. plaster of Paris

  3. a pearl

  4. an ultramarine

Show answer
Correct Option: B
Explanation:
It is prepared by heating Gypsum to a temperature of 373K. When gypsum is heated to a temperature of 373K, it loses three-fourths of its water of crystallization and forms Plaster of Paris.
$\underset{\text{Gypsum}}{CaS{O} _{4}.2{H} _{2}O} \xrightarrow[373 K]{\Delta} \underset{\text{Plaster of Paris}}{CaS{O} _{4}.\cfrac{1}{2}{H} _{2}O} + \cfrac{3}{2}{H} _{2}O$

The alkali metals form strong bases, salts and stable carbonates. Which of the following elements does not belong to this chemical family?

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

  1. Potassium

  2. Sodium

  3. Lithium

  4. Magnesium

Show answer
Correct Option: D
Explanation:

$Mg$ does not belong to alkali metal family. Moreover carbonates of $Mg$ are less stable.

A suitable site of a cement plant requires proximity to:

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

  1. limestone and gypsum

  2. limestone and manganese

  3. coal and iron

  4. coal and gypsum

Show answer
Correct Option: A
Explanation:

Hydrated lime is added to sand and cement so that they don't separate and gypsum is used so that it sets well with the iron pillars or bricks,etc.