Tag: the s-block elements (alkali and alkaline earth metals)

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Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

The metal ions (charged particles) that are required for contraction of muscles in human beings and animals are ions of:

  1. calcium

  2. sodium

  3. potassium

  4. iron
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$Ca^{2+}$ ions are required for contraction of muscles in humans.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

Which of the following metals is required as a cofactor by all enzymes utilizing ATP in phosphate transfer?

  1. K

  2. Ca

  3. Na

  4. Mg
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mg binds to phosphate group in ATP thus making a complex that catalyses phosphate transfer. 

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

The main constituents of pearl are:

  1. ammonium sulphate and sodium carbonate

  2. aragonite are conchiolin

  3. calcium carbonate and magnesium carbonate

  4. calcium oxide and ammonium chloride
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The chief component of the nacre that constitutes the pearl is aragonite $(CaCO _3)$. Nacre also contains a small amount of conchiolin, a hornlike organic substance (albuminoid) that is the main constituent of the mollusk's outer shell.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

Which of the following statements is/are false?

  1. The halides of beryllium are electron deficient and are polymeric with halogen bridges.
  2. $BeF _2$ is very soluble in water owing to high solvation energy of Be but fluorides of other alkaline earth metals are almost insoluble.

  3. CaO, SrO and BaO react exothermically with water forming soluble hydroxides.

  4. The bicarbonates of alkaline earth metals are only stable in solutions.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements biological importance of sodium and potassium

Select correct statement(s).

  1. $Mg^{2+}$ ions are necessary for the activation of phosphate transfer enzymes.

  2. Mg is present in chlorophyll of green plants.

  3. Mg is present in chlorophyll used in photosynthesis in green plants.

  4. All the above are correct statements
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mg2+ is indeed a cofactor for phosphate transfer enzymes (like kinases) and is the central atom in chlorophyll, which is used in photosynthesis.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) biological importance of magnesium and calcium biological importance of elements biological importance of s block elements

Bones and teeth contain:

  1. Calcium dihydrogen phosphate

  2. Apatite

  3. Calcium phosphide

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bones and teeth contains Apatite which is a group of phosphate minerals and contains calcium. Its formula can be represented as $Ca _5(PO _4) _3(F,Cl,OH)$.

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Which of the following compounds on thermal decomposition yields a basic as well as an acidic oxide?

  1. $KClO _3$
  2. $NaNO _3$
  3. $K _2CO _3$
  4. $MgCO _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$MgCO _3\xrightarrow{\Delta} MgO+CO _2$

Since oxides of metals are basic in nature, $MgO$ is basic, and $CO _2$ is acidic. Hence decoposition of $MgCO _3$ yields both acidic and basic oxides

Multiple choice chemistry the s-block elements (alkali and alkaline earth metals) anomalous properties of lithium group 1 elements: alkali metals properties of s block elements

Which nitrate will decompose to give $NO _2$ on heating?

  1. $NaNO _3$
  2. $KNO _3$
  3. $4RbNO _3$
  4. $LiNO _3$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Only $LiNO _3$ gives $NO _2$ on heating. All other nitrates give oxygen.
$4LiNO _3 \, \xrightarrow{\Delta} \, 2Li _2O \, + \, 4NO _2 \, + \, O _2.$
$2NaNO _3 \, \xrightarrow{\Delta} \, 2NaNO _2  \, + \, O _2$