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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

A holoenzyme contains apoenzyme and ____________ .

  1. isoenzyme

  2. cofactor

  3. inhibitor

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

Holoenzyme = Apoenzyme+ Cofactor.

Apoenzyme:-An apoenzyme is an inactive enzyme, activation of the enzyme occurs upon binding of an organic or inorganic cofactor.
Cofactor:-A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's activity

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

For a given sample of water containing the following impurities
$Mg{ \left( H{ CO } _{ 3 } \right)  } _{ 2 }=73mg/L;\quad Ca{ \left( H{ CO } _{ 3 } \right)  } _{ 2 }=162mg/L;\quad Ca{ SO } _{ 4 }=136mg/L$
$Mg{ Cl } _{ 2 }=95mg/L;\quad Ca{ Cl } _{ 2 }=111mg/L;\quad NaCl=100mg/L$
Then the total hardness (temporary and permanent) of above water sample is

  1. $300ppm$
  2. $350ppm$
  3. $450ppm$
  4. $500ppm$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total hardness is calculated based on the concentration of Ca2+ and Mg2+ salts expressed as CaCO3 equivalents. Using molar masses (Mg(HCO3)2=146, Ca(HCO3)2=162, CaSO4=136, MgCl2=95, CaCl2=111), the calculation yields 300 ppm.

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 hydrogen ion scale or the ph scale inorganic analysis chemical analysis and investigation practical work chemistry

What is litmus?

  1. Water soluble mixture of different dyes.

  2. Mixture of metal and non-metal ions.
  3. Both $A$ and $B$

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

Litmus is a water-soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, colors the red litmus paper blue.