Explore topic-wise InterviewSolutions in Current Affairs.

Ionic compounds contain ions become mobile in molten state and conduct electricity whereas in solid form, ions are fixed in a lattice and the compound does not conduct electricity.

2Al + 3CuCl₂ → 2AlCl₃ + 3Cu

(a) On exposure to air, aluminium forms a hard protective layer of aluminium oxide (N₂O:) which prevent further oxidation.
(b) Magnesiurn oxide is an  oxide of a metal, so, it is basic in nature. Due to its basic character, it turns red litmus paper blue when touched with its aqueous solution.

The blackness of silver coin is due to the formation of silver sulphide on its surface due to its exposure to air. On boiling, the aluminium foil reacts with the layer of silver sulphide and displaces silver from silver sulphide to form aluminium sulphide and silver. This makes the coin shiny.
3Ag2S + 2Al -----> 6Ag + Al₂S₃

The reaction in which oxygen combines with other elements or compounds is known as an oxidation reaction. For example, burning of hydrogen is an oxidation process in which hydrogen combines with oxygen to form water.
2H₂(g) + O₂(g) --------> 2H₂O(I)
Oxidation reactions are exothermic.

(a) physical change    

(b)chemical change   

(c) physical change 

(d)chemical change

(e) physical change 

AgNO₃(aq) + NaCl(aq)   -----> AgCl(s) ↓+  NaNO₃(aq)
Silver nitrate      Sodium chloride    Silver chloride (ppt.)   Sodium nitrate

In this equation, oxygen should be in a molecular form (O₂) as oxygen exists as biomolecular gas 

O₂. 2Mg + O₂ ----> 2MgO

Consider the following displacement reaction in which Fe displaces Cu from CuSO4 to form FeSO4:

Fe(s) +              CuSO4(aq) ---->       FeSO4(aq) +   Cu(s)
Iron          Copper sulphate     Iron (ll)  sulphate      Copper
(Blue)                                         (Green)                  (Reddish-brown)
In the above reaction, Fe is gaining oxygen.Hence, Fe is oxidised. CuSO4 is loosing oxygen.
Hence, it is reduced. So, it is a redox reaction.

Rice, potatoes and bread contain carbohydrates. During digestion, these carbohydrates are broken down into a  simpler substance called glucose. Digestion follows respiration. During respiration, the glucose combines with oxygen in the cells of our body and provides energy. Thus, respiration is an exothermic process because energy is produced during this process.
C₆H₁₂O₆(aq) + 6O₂(9) + 6H₂O(l) -----> 6CO₂(g) +12H₂O(I) + Energy
Glucose

On mixing the clear solutions of two ionic compounds, a substance which is insoluble in water, is formed. This insoluble substance formed is known as precipitate. Any reaction that produces a precipitate is called a precipitation reaction.
When sodium sulphate solution is mixed with barium chloride solution, a white substance BaSO₄ is formed.
Na₂SO₄(aq) + BaCl₂(aq) --------> BaSO₄(s)↓ +2NaCl(aq) 

The white precipitate of BaSO₄ is formed by the reaction of SO₄^-2and Ba²⁺. The other product formed is sodium chloride which remains in the solution.

(a) Oxidation: It is defined as a process which involves gain of oxygen. For example,
(i) 2Mg(s) + O₂(g)  ----->  2MgO(s)
Magnesium  Oxygen Magnesium oxide 

Here, Mg has gained oxygen to form MgO. Hence, Mg has been oxidised to MgO.
(ii) 2Cu(s) + O₂(g)  Heat  -----> 2CuO(s)
Copper           Oxygen          Copper oxide
In this reaction, Cu has gained oxygen to form CuO. Thus, Cu is oxidised to copper oxide (CuO).
(b) Reduction: It is defined as the process which involves loss of oxygen. For example,
(i) Cuo + H₂ +Heat ------>    Cu + H₂O
Copper oxide    Hydrogen             Copper  Water
In this reaction, copper oxide is losing oxygen. So, it is being reduced to copper.

2FeSO₄(s) +Heat -----> Fe₂O₃(s) + SO₂(g) + SO₃(g)
It is a thermal decomposition reaction.

(i) Double displacement reaction
(ii) Displacement reaction
(iii) Combination reaction

(i) The substance getting oxidised is H₂.
(ii) The substance getting reduced is CuO.

(iii) CuO s the oxidising agent.
(iv) H₂ is the reducing agent.
(v) Since oxidation and reduction taking place simultaneously, this reaction is an example of redox reaction.

(i) The temperature of the reaction mixture rises when aluminium is added because it is an exothernic reaction.
(ii) Reaction of sodium metal is found to be highly explosive because it is an exothermic reaction.
(iii) When lead is treated with hydrochloric acid, bubbles of hydrogen gas are evolved.
Pb(s) + 2HCl(aq) ------> PbCl₂(aq) + H₂(g)

A chemical analysis uses only a small fraction of the available sample, the process of sampling is a very important operation. Knowing how much sample to collect and how to further subdivide the collected sample to obtain a laboratory sample is vital in the analytical process.

The main steps that are performed during a chemical analysis are the following: 

(1) sampling, (2) field sample pretreatment, (3) laboratory treatment, (4) laboratory assay, (5) calculations, and (6) results presentation. 

Each must be executed correctly in order for the analytical result to be accurate.

Vitamin B12 is a nutrient that helps keep the body's nerve and blood cells healthy and helps make DNA, the genetic material in all cells. Vitamin B12 also helps prevent a type of anemia called megaloblastic anemia that makes people tired and weak.

Folate as a coenzyme is involved in the transfer and utilization of Single carbon moiety.

(a) Both assertion and reason are true, reason is correct explanation of assertion

An increase of atomic number is in the order, H < Li

Energies of the orbitals in the same subshell decrease with an increase in the atomic number. 

Hence, 2s orbital (energy level) of Li will be less than H

According to this,
n+l rule,
3d and 4p have same energy as
3+2 =5 4+1 =5
similarly, 4d and 5p have same energy.

b)

•  For subshells with the same value of (n+ℓ), electrons are assigned first to the sub shell with lower n. 
• A version of the aufbau principle known as the nuclear shell model is used to predict the configuration of protons and neutrons in an atomic nucleus.

Now we take a question to understand it clearly:

Q. n and l values of an orbital A are 3 and 2 and for other orbital B are 5 and 0. The energy of :

A) B is more than A

B) A is more than B

C) A and B are same

D) A is 4 times than B

Sol. Electrons are assigned to orbitals in order of increasing value of (n+l). For subshells with the same value of (n+l), electrons are assigned first to the subshell with lower n.

For orbital A,n = 3, l = 2, therefore, n+l=5

For orbital B,n = 5, l = 0, therefore, n+l =5

So, larger the n, greater is the energy.

So, the energy of B > energy of A.

c) (i)

• The exactly half-filled and fully filled orbitals have greater stability than other configurations. 
• The reason for their stability are symmetry and exchange energy. 
• The half-filled and fully-filled orbitals are more symmetrical than any other configuration and symmetry leads to greater stability.

(ii) 

• The half-filled and fully-filled orbitals are more symmetrical than any other configuration and symmetry leads to greater stability. 
• The electrons present in the different orbitals of the same sub-shell can exchange their positions. 
• Each such exchange leads to the decrease in energy known as Exchange Energy

The energy of an electron in its nth orbit = -13.6/n².
T.E in first excited state = -13.6/4 = -3.4 eV
PE in the first excited state = -6.8 eV.
(as PE:TE = 2:1)

For this to be zero, we must add +6.8.

So, +6.8 

Formula of lead iodide is PbI₂ and that of potassium nitrate is KNO₃.

reaction is as follows-

Pb(NO₃) + KI = KNO₃ + PbI₂

• yes the precipitate is yellow in colour.
• double displacement reaction
• because when they are mixed,they exchange their ions...

Correct option (4) C–4   

Explanation:

Glucose and galactose differs in configuration on C_4-

=> The molar mass of Calcium Carbonate is 100 g/mole, 

We have 200 g, therefore, we have 2 moles, 

the number of molecule per mole is 6.02 x 10²³, 

Therefore we have 1.204 x 10²⁴ molecules.

=> Molecular mass of CaCO3 = 40 + 12 + (3 x 16) = 100 g [Molecular weight of Ca = 40, C = 12, O =16]

1 mole of Oxygen atoms = 6.022 x 10²³ Oxygen atoms (Avogadro’s number)

1 mole of Calcium Carbonate = 100 g of Calcium Carbonate

100 g of Calcium Carbonate has 3 moles of Oxygen atoms = 3 x 6.022 x 10²³ Oxygen atoms.

So, 200 g of Calcium Carbonate has 6 moles of Oxygen atoms = 6 x 6.022 x 10²³ Oxygen atoms.​

F vector is given in question and r vector = difference of two points

Now, Use the formula to get the answer

Moment of force = F vector × r vector

Correct option is A) take up

Correct option is C) take over

Correct option is A) takes off

Correct option is A) take to

Correct option is C) some

Correct option is A) will have to

The film was funny At the end. 

Correct option is B) come around

Correct option is B) claims

1. The management arrived at a decision.

2. The train went through a tunnel.

3. We congratulate you on your success.

4. He is walking along the road to Bangalore.

5. The athletes ran over the hurdles.

Correct option is D) buy

Correct option is B) adjust

Correct option is C) had met

Correct option is D) would have

Correct option is D) Asking questions

Correct option is A) Would he have

Correct option is B) would have been destroyed

Correct option is D) me to go

Correct option is B) me to do

Correct option is D) Did you have

Correct option is A) She / in

Correct option is C) It's cold / it's going to

Correct option is B) up

Correct option is C) Did / ate / when