Tag: chemistry

Questions Related to chemistry

Ethers are heated with excess of conc. hydrogen halide to give alkyl halide, then the reactivity order of hydrogen halide is :

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. $HCl < HBr < HF$

  2. $HI > HBr > HCl $

  3. $HF < HCl < HBr $

  4. none of these

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Correct Option: B
Explanation:

When $HX$ is in excess and reaction is carried out at high temperature. Iodine is a good nucleophile, displaces an alcohol molecule by $SN^2$ mechanism thus $HI>HBr>HCl$

Ethyl phenyl ether on boiling with conc. HBr gives: 

chemistry hydroxy compounds and ethers chemical properties of ethers ethers alcohols, phenols and ethers

  1. phenol and ethane

  2. bromobenzene and ethane

  3. phenol and ethyl bromide

  4. bromobenzene and ethanol

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Correct Option: A

$MCrO _{4(s)}\overset{CH _{3}COOH(aq)}{\rightarrow}MCrO _{4}$  ( Suspension) above change is correct for which metal ion (s) ? 

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $Ba^{2+},Sr^{2+},Ca^{2+}$

  2. $Ba^{2+},Sr^{2+}$

  3. Only $Ba^{2+}$

  4. $Sr^{2+},Ca^{2+}$

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Correct Option: C

Which is the major constituent of gun powder?

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. Nitre

  2. Sulphur

  3. Charocal

  4. Chile salt petre

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Correct Option: A
Explanation:

Gunpowder is a mixture of sulphur, charcoal and potassium nitrate (nitre). Among these Potassium Nitrate (saltpeter) is major constituent of gun powder.

The common name, "cream of tartar" refers to :

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $KHC _{4}H _{4}O _{6}$

  2. $K(SbO)C _{4}H _{4}O _{6}$

  3. $KNaC _{4}H _{4}O _{6}$

  4. $Mg _{2} (OH) _{2}(C _{4}H _{4}O _{6})H _{2}O$

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Correct Option: A
Explanation:

Cream of tartar : Potassium bitartrate(potassium hydrogen tartrate) $KHC _4H _4O _6$

$Sr^{2+}$ forms a very unstable complex with $NO _{3-}$. A solution that was $0.001 M - Sr(ClO _{4}) _{2}$ and $0.05 M - KNO _{3}$ was found to have only $75$% of its strontium in the uncomplexed $Sr^{2+}$ form, the balance being $Sr(NO _{3})^{+}$. What is $K _{f}$ for complexation?

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $6.67$

  2. $0.15$

  3. $60$

  4. $26.67$

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Correct Option: A

Potash alum is represented by the formula :

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $K _2SO _4\cdot Al _2(SO _4) _3\cdot 24H _2O$

  2. $K\cdot Al(SO _4) _2\cdot 12 H _2O$

  3. Both (a) and (b)

  4. None of these

Show answer
Correct Option: B
Explanation:

Potassium alum or potassium aluminium sulphate is a chemical compound with a chemical formula $KAl(SO _4) _2$ and it is commonly found in its dodecahydrate form as $KAl(SO _4) _2.12H _2O$. 


Alum is the common name for this chemical compound.

$KO _2$ (potassium superoxide) is used in oxygen cylinders in space and submarines because, it : 

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. decomposes to give oxygen

  2. eliminates moisture

  3. absorbs $CO _2$

  4. produces ozone

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Correct Option: A,C
Explanation:

$KO _2$ on decomposition give oxygen and pottassium carbonate.The oxygen is used in oxygen cylinders in space and submarines
$2CO _2+4KO _2\rightarrow 3O _2+2K _2CO _3$.
Hence option A is correct.

In the reaction : $K _4[Fe(CN) _6] + K _2CO _3\rightarrow $ the product formed is :

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. $FeCO _3$

  2. $KCN$

  3. $KFeCO _3$

  4. $K _3 [Fe(CN) _6]$

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Correct Option: B
Explanation:

$K _4Fe(CN) _6+K _2CO _3\rightarrow 5KCN+KCNO+Fe+CO _2$.

In the above reaction only KCN is formed.

Hence, option B is correct.

${K} _{2}C{S} _{3}$ can be called potassium :

chemistry the s-block elements (alkali and alkaline earth metals) uses of alkali and alkaline earth metals uses of s block elements group 1 elements: alkali metals

  1. Sulphocyanide

  2. Thiocarbide

  3. Thiocarbonate

  4. Thiocyanate

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Correct Option: C