Tag: chemistry

Questions Related to chemistry

Which of the following is not the unit of atmosperhic pressure?

chemistry the particle theory atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. $Pascal$

  2. $N/m^2$

  3. $N/m$

  4. $76\ cm\ of\ Hg$

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Correct Option: C
Explanation:

The unit of the pressure is $pascal$. $N/m^2$, and $76\ cm\ of\ Hg$.

Here $N/m$ is the unit of the surface tension. 
Thus option C is the correct answer.

The atmospheric pressure remains unchanged throughout the earth's atmosphere.

chemistry the particle theory atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. True

  2. False

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Correct Option: B
Explanation:

The atmospheric pressure changes throughout the atmosphere.
Example: As we go up in the air, the atmospheric decreases as the density of the air decreases. 

Usually the atmospheric pressure is equal to ___________.

chemistry the particle theory atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. $1.013\times 10^{5}$ Pascal

  2. $1.013\times10^{5}N/m^2$

  3. $101.3\ kPa$

  4. all of the above

Show answer
Correct Option: D
Explanation:

The atmospheric pressure can be given as $1.013\times 10^{5}\ pascals$ or $1.013\times10^{5}\ N/m^2$.

Pressure can be measured by using Mercuric as well as Aneroid barometer.

chemistry the particle theory atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

In 1643 Torricelli made an instrument for measuring atmospheric pressure. This device is called a barometer. This barometer can be either mercuric or aneroid barometer. 

In human body, the pressure exerted by the cells is ________ the atmospheric pressure.

chemistry the particle theory atmospheric pressure and boiling point evaporation - factors and effects in daily life changes in physical state - boiling, evaporation and condensation

  1. equal to

  2. more than

  3. slightly greater than

  4. greater than

Show answer
Correct Option: A
Explanation:

In the human body, the pressure exerted by the cells in our body is equal to the atmospheric pressure. Hence we do not get shrunk.

Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state? 

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $Ag _2SO _4$

  2. $CuF _2$

  3. $ZnF _2$

  4. $Cu _2Cl _2$

Show answer
Correct Option: B
Explanation:
The respective transition elements exists in
$Ag^{+}-{4d}^{10}5s^0$, (have completely filled d orbital)
$Cu^{+2}-3d^{9}4s^0$, (have incompletely filled d orbital)
$Zn^{+2}-3d^{10}4s^0$ , (have completely filled d orbital)
$Cu^{+1}-3d^{10}4s^0$ (have completely filled d orbital),
Since, $Cu^{+2}$ has unpaired electron it will show electron transitions. 
Hence will be coloured.

In which of the following ions, the colour is not due to $d-d$ transition?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $[Ti(H _2O) _6]^{3+}$

  2. $[Cu(NH _3) _4]^{2+}$

  3. $[CoF _6]^{3-}$

  4. $CrO _4^{2-}$

Show answer
Correct Option: D
Explanation:
Colour is due to d-d transtition ,then such complexes have colour due to d-d transition are surely octahedral complexes.
Among the given options,                                                   
                                         ${ \left[ Ti{ \left( { H } _{ 2 }O \right)  } _{ 6 } \right]  }^{ 3+ }$
                                        ${ \left[ Cu{ \left( { NH } _{ 3 } \right)  } _{ 4 } \right]  }^{ 2+ }$
                                           ${ \left[ { COF } _{ 6 } \right]  }^{ 3- }$
This are octahedral complexes.
$CrO _4^{2-}$ is a salt,it colour is not due to d-d transition.

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) $FeSO _4.7H _2O$ (i) Green
(B) $NiCl _2.4H _2O$ (ii) Light Pink
(C) $MNCl _2.4H _2O$ (iii) Pale green
(D) $CoCl _2.6H _20$ (iv) Pink
(E) $Cu _2Cl _2$ (v) Colourless
chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. (A) - (iii), (B) - (iv), (C) - (i), (D) - (ii), (E) - (v)

  2. (A) - (ii), (B) - (iii), (C) - (iv), (D) - (i), (E) - (v)

  3. (A) - (v), (B) - (ii), (C)-(iii), (D) - (iv), (E) - (i)

  4. (A) - (iii), (B)-(i), (C)-(ii), (D) - (iv), (E).- (v)

Show answer
Correct Option: D
Explanation:

The colour of the following compounds are:

(i) $FeSO _4$. & $H _2O$ - Pale green.
(II) $NiCl _2$.$4H _2O$ -Green
(iii) $MnCl _2$.$4H _2O$ - Light pink
(iv) $CoCl _2$.$6H _2O$ - Pink
(v) $CuCl _2$ - Colourless.
The colour of the transition metal compounds is due to partially filled d orbitals. Due to that,  d-d transition its complementary colour is seen. 
Hydrated complexes are coloured because in that come H$ _2$O molecules act as a ligand and gets arranged around the central metal atom so as to bring d-d transition.

For $Zn^{2+}$, $Ni^{2+}$, $Cu$, and $Cr^{2+}$ which of the following statements is correct?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. Only $Zn^{2+}$ is colourless and $Ni^{2+}$, $Cu^{2+}$ and $Cr$ are coloured

  2. All the ions are coloured

  3. All the ions are colourless

  4. $Zn^{2+}$and $Cu^{2+}$ are colourless while $Ni^{2+}$ and $Cr^{2+}$ are coloured

Show answer
Correct Option: A
Explanation:

Since $Zn^{+2}$ have fully filled $d$ orbital having no unpaired electrons,it does not undergo electronic transitions,hence colourless.However,rest of the elements given as $Ni^{+2}$ , $Cu^{+2}$ and $Cr^{+2}$ has unpaired electrons which can undergo electronic transitions and hence show colours.

Which of the following group contains coloured ions?
1. $Cu^+$
2. $Ti^{4+} $
3. $Co^{2+}$
4.  $Fe^{2+}$

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $1,4$

  2. $3,4$

  3. $2,3$

  4. $1,2$

Show answer
Correct Option: B
Explanation:

$Cu^{+}$ and $Ti^{+4}$ have fully filled and empty d orbital respectively. Hence due to absence of unpaired electrons,they will be colourless. But $Fe^{+2}$ and $Co^{+2}$chave unpaired electrons. Hence they will be coloured.