Explore topic-wise InterviewSolutions in Current Affairs.

(i) It includes ions of alkali metals, alkaline earth metals, lighter transition metals in higher oxidation states. 

Ex: Ti⁴⁺, Cr³⁺, Fe³⁺, CO³⁺ and H⁺ 

(ii) Small size, high polarising power, high electro negativity and high positive oxidation state are the characteristic features of hard acids. 

(iii) Their outer electrons or orbitals are not easily distorted.

Note : 

(i) It should be remembered that we are considering ions like Li⁺ , Na⁺ etc. These ions are highly electronegative because their subsequent ionisation energies are very high.

(i) It is a simple rule to predict qualitatively the relative stability of acid - base reactions. 

(ii) "Hard acids prefer to bind to hard bases and soft acids prefer to bind to soft bases". Thus the complex A : B is the most stable when both A and B are either hard or soft. 

(iii) However, when one of the reactants is very hard and the other very soft, the complex will not be much stable. 

(iv) Hard-hard interactions involve ionic bonding and soft-soft interactions result primarily from covalent bonding. 

(v) Soft-soft interaction can be explained on the basis of π-bonding. Soft acids have low oxidation states and possess large number of d-electrons. Thus they can act as π-bond donors and soft bases are generally π-bond acceptors. The presence of d-orbitals on the ligands (except on CO) helps to strengthen the π-bonding.

In R-S Nomenclature, -SO3H is senior most than -COOH

Hard Acids : 

(i) It includes ions of alkali metals, alkaline earth metals, lighter transition metals in higher oxidation states. 

Ex: Ti⁴⁺, Cr³⁺, Fe³⁺, CO³⁺ and H⁺. 

(ii) Small size, high polarising power, high electronegativity and high positive oxidation state are the characteristic features of hard acids. 

(iii) Their outer electrons or orbitals are not easily distorted.

Soft Acids : 

(i) It includes ions of the heavier transition metals and those in lower oxidation states. 

E x . Cu⁺ , Ag⁺ , Hg₂²⁺, Pd²⁺, Pt²⁺ and Hg²⁺. 

(ii) They are large sized and their outer electrons or orbitals are easily distorted. They have low polarising power and low electronegativity.

The correct option (4) S₁ is false, S₂ is true  

Explanation:

Conductivity decreases on decreasing concentration of electrolyte.

Molar conductivity increases on decreasing concentration of electrolyte.

Now, let the quantity of Zinc to be added be y kg

The initial total quantity of German Silver is 54 kg

Hence, we can obtain the initial quantities of the various metals as:

After y kg of zinc is added, the ratio of copper, zinc and nickel becomes 2 ∶ 5 ∶ 1. 

So, let the new respective quantities of these metals be 2x, 5x, and x respectively.

Hence, x = 12

Therefore, the new quantity of zinc becomes:

18 + y = 5x      ----(i)

On substituting the value of x = 12 into the equation (i), we get:

y = (5 × 12) – 18 = 42

∴ The required quantity of zinc to be added is 42 kg

(i) Oxygen in H₂O is more electronegative than in H₂S 

(ii) Because cone. H₂SO₄ removes water molecule from others substances

Correct option is (A) (D) > (B) > (C) > (A)

(A) n + l = 3 + 0 = 3

(B) n + l = 4 + 0 = 4

(C) n + l = 3 + 1 = 4

(D) n + l = 3 + 2 = 5

Higher n + l value, higher the energy & if same n + l value, then higher n value, higher the energy.

Thus: D > B > C > A.

Option : (A) Na⁺[X_eF₇]^-

NaF + X_eF₆ → Na⁺[X_eF₇]^-

Correct option is (D) 6600 kJ

C(S) + O₂(g) → CO₂(g) + 400 kJ 

1 g mole

C(s) + 1/2 O₂ (g) → CO (g) + 100kJ ..... 2  (II)

0.6 x 1000

= 600 gm

600 x 60/100 (Pure Carbon)

= 360 gm = 360/12 = 30 mole (Pure Carbon)

Carbon converted into CO₂ = (30 - 30 x 60/100)

= 12 mole 

and carbon converted in CO = 30 x 60/100 = 18 mole

Energy generated during II equation 

= 18 x 100 = 1800 kJ 

Energy generated during 1^st reaction. 

= 12 x 400 

= 4800 

Total = 1800 + 4800 = 6600 kJ

Correct option is (A) He 

More the critical temp. of gas greater is the ease of liquefaction hence greater is the adsorption.

Option : (C) (±) - Butan - 2 - ol

(±) Butan - 2 - ol, is optically inactive, because it is mixture of two enantiomers with equal ratio. they form racemic mixture. racemic mixtures are optically inactive.

One mole of H2SO4 ​ gives 2 mole H⁺ ions. 

[H⁺] ion concentration in 0.01M H₂SO₄ ​ =0.01×2=0.02 mole/l 

pH=−log[2×10⁻²]=1.699

Option : (B) Halogens are more reactive than interhalogens.

Inter halogen compound are more reactive than all halogens. because-bond energy of inter halogens compounds is less than the bond energy of halogens.

Option : (D) C₂H₅-I

The boiling points of C₂H₅ - X (ethyl halide) increases down the group due to increase in the Vander waals forces of attraction with the increases in the size and mass of halogen atom.

Hence,

C₂H₅I has highest boiling point.

Correct answer is (B) Butadiene and Styrene

Correct answer is (A) Phenol

Correct answer is (D) All of these

Correct answer is (C) Acetyl salicylic acid

Correct answer is (D) Tranquilizer

People living in the hilly areas are exposed to the strong rays of the sun because of which they get sunburns. Sunburns are normally caused due to the ultraviolet rays present in the sunlight which has the intense heating effect causing the skin to get reddened. 

This effect is not generally observed near the sea regions because the sun rays are not that strong near the sea surface in technical terms the intensity of sun rays is less at sea level.

घर के पास हमारे लिए उपयोग की वस्तुएँ बनाने के लिए जो छोटे उद्योग स्थापित किये जाते हैं उन्हें घरेलू -उद्योग कहते हैं। लुहार (लोहे का काम करना), कुम्हार (मिट्टी से बर्तन बनाना), जुलाहा (कपडे बुनना), बढ़ई (लकड़ी से सामान बनाना), सुनार (सोने और चाँदी के ज़ेवर बनाना), बंसोर (बांस से ‘सामान बनाना) आदि घरेलू उद्योग हैं।

a. Biological control

Family of the Bemisia tabaci Aleyrodidae. 

b. Limit the movement of the pest 

(1) Cytokinin

Number of insects per leaf , Number of insects per plant & Number of insects per twig

d. None of these 

A beetle that feeds on kudzu is likely to be regarded as the most "useful" biological control agent.

Host of the Entomophthora muscle  Housefly.

c. Ants and plant-feeding insects that produce honeydew (e.g., aphids and scale insects) 

Breeding nursey stock for higher levels of secondary plant compounds would be an example of Antixenosis.

Serratia marcescent belongs to the group Bacteria.

e. All of the above

Ototoxic is chemical toxic to Ear.

NPV pathogen belongs to the group Virus.