Explore topic-wise InterviewSolutions in Current Affairs.

Correct Answer is: (c) Dry forests

Correct answer is (D) volt

Correct answer is (C) Work

P = 2 (l + b) ± 2 (∆l + ∆b) 

= 2(10.5 + 5.2) ± 2(0.2 + 0.1) 

= (31.4 ± 0.6) cm.

Correct answer is (C) Distance

Correct answer is (C) 2%

About learned men, Hazlitt says that they are a kind of men who are untiring readers of books .They have no ideas of their own and are incapable of making independent observations on any subject. They do not possess true knowledge as they are content with sense borrowed from others.

विद्वान व्यक्तियों के बारे में Hazlitt का कहना है वे इस प्रकार के व्यक्ति होते हैं जो पुस्तकों के कभी न थकने वाले पाठक होते हैं। उनके पास खुद के कोई विचार । नहीं होते और किसी भी विषय पर स्वतन्त्र विचार रखने में असमर्थ होते हैं। उनके पास सच्चा ज्ञान नहीं होता क्योंकि वे दूसरों से लिये हुये ज्ञान से सन्तुष्ट होते हैं।

Hazlitt believes that the learned people are mere scholars who know nothing but books. They have no real knowledge of men and things connected with practical life. They do not know what happens around them and are ignorant of the language and beauty of nature and art and other aspects of life

Hazlitt का मानना है कि विद्वान लोग केवल ऐसे ज्ञानी होते हैं जो पुस्तकों के अलावा कुछ नहीं जानते। उनके पास व्यवहारिक जीवन से जुड़े लोगों और बातों का कोई वास्तविक ज्ञान नहीं होता। उन्हें नहीं पता कि उनके आस-पास क्या हो रहा है और प्रकृति और कला की भाषा और सौन्दर्य और जीवन के दूसरे पहलुओं के बारे में वे अनजान होते हैं।

Solution A (pH = 3.0) will turn litmus from solution blue to red Solution B (pH = 9.5) will turn phenolphthalein from colourless to pink.

The pH of:

(a) Pure water is 7

(b) Milk is 6.6

(c) Human blood is 7.3

Solution Y is a stronger acid.

pH value of a solution is the negative logarithm to the base 10 of hydrogen ion concentration expressed in gram-ions per litre.

• pH value = 7 indicates a neutral solution.
• pH value > 7 indicates an alkaline solution.
• pH value < 7 indicates an acidic solution.

(iv) only d, is correct

1. Pink solution becomes colourless.

2. Orange solution changes to red or pink.

3. It turns red

(a) Acidity of soil is reduced by adding slaked lime.

(b) Antacid tablets are given to a person suffering from acidity.

Is red in acid solution but turns blue in basic solution-

Litmus.

(a) Red.

(b) Red.

Indicators are complex organic compounds, which are used to distinguish between acidic and alkaline solutions by the abrupt change in their colour, e.g. litmus, methyl orange and phenolpthalein.

The three indicators and their colours in different medium are given below:

Oxygen being smallest in size is capable of forming pπ - pπ bond and exists as O = O. (O₂ molecule) while sulphur being larger in size is not able to form pπ - pπ bond.

The common name of propanone is-

Acetone

(i) Cu +2H₂SO₄→ CuSO₄ +SO₂+2H₂O

(ii) SO₃+H₂O →  H₂SO₄

H₂SO₄ ionises in two stages and hence has two dissociation constants. K_a2 << K_a1.

This is because the negatively charged HSO₄^- ion has much less tendency to donate a proton to H₂O as compared to neutral H₂SO_4.

A reactivity series is a list of metals which are arranged in the order of their decreasing activity. This means the metal at the top of the series is the most reactive and the metal at the bottom of the list is the least reactive metal. 

To develop a reactivity series, take pieces of different metals (e.g., iron, copper, zinc etc) and the salt solutions of those metals (i.e., iron sulphate, copper sulphate, zinc sulphate etc). 

Add a metal piece to a different metal salt solution. Check for any colour changes in the solution or to the metal piece and record your observations. 

One can tell that for metals A and B if the following reaction occurs,

Metal A + salt solution of B → metal B + salt solution of A 

Then, metal A is more reactive than B. Similarly by trying out various combinations of metals with metal salt solutions, one can create a reactivity series.

XeF₂ + PF₅ →  [XeF]⁺ + [PF₆]^-

XeF₂ + 4 PF₅ = XeF₆ + 4 PF₆

The different system of measurement are English system and the metric system.

The S.I. unit of mass is kilogram (kg). A kilogram is equal to the mass of platinum-iridium cylinder kept at the International Bureau of Weights and Measures at Service, France.

Physical properties are those properties which can be measured or observed without changing the identity or the composition of the substance whereas the measurement of chemical properties require a chemical change to occur e.g. colour, odour etc are physical properties and combustion, basicity etc are chemical properties.

• The mass of a single atom is extremely small, i.e. the mass of a hydrogen atom is 1.6736 × 10^-24g. Hence, it is not possible to weigh a single atom.
• In the present system, mass of an atom is determined relative to the mass of an atom of carbon-12 as the standard. This was decided in 1961 by international agreement.
• The atomic mass of carbon-12 is assigned as 12.00000 atomic mass unit (amu).
• The masses of all other elements are determined relative to the mass of an atom of carbon-12 (C-12).
• The atomic masses are expressed in amu which is exactly equal to one twelth of the mass of one carbon-12 atom.
• The value of 1 amu is equal to 1.6605 × 10^-24 g.

Correct option: (C) Titration

(D) Distilled water

A mixture is a material that is made up of two more chemical compounds or substances that do not combine together chemically. these chemical compounds or substances are not in fixed proportion. Like Gasoline, Paint, LPG.

While in water (\(H_2O\)), Hydrogen and oxygen are present in fixed proportion.

Therefore, \(H_2O\) is a compound not a mixture.

Option : (D) Distilled water

Correct option: (A) Empirical formula

(B) mixture

The mixture show, the properties of its constituent substance while the compounds show different properties to its constituent (substance).

Option : (B) mixture

The components of a mixture can be separated by physical methods like handpicking, filtrations, crystallization, distillation etc.

Correct option: (C) percentage composition

Molecular formula = (Empirical formula)_n, where n is a positive integer.

(i) 6.454, (ii) 48.38, (iii) 7.000 × 10⁴, (iv) 2.660 × 10³, (v) 0.004687.

The constituents of a compound can not be separated by physical methods. They can only be separate by chemical methods.

Mass percentage of an element in a compound

= {Total mass of the element in one molecule}/{Gram molecular mass of the compound} x 100

The formula mass of a molecular substance is the sum of atomic masses of all atoms is a formula unit of the compound.

Answer is 0.0561

(i) 208.91 has five significant figures. 

(ii) 0.00456 has three significant figures. 

(iii) 453 has three significant figures. 

(iv) 0.346 has three significant figures. 

According to this law, if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers.

(3.24 x 0.08666)/5.006 = 0.0560883 (Actual result) As 3.24 has least number of significant figures, viz., 3, the result should contain 3 significant figures only. Hence, the result will be reported as 0.0561 (after rounding off).

(I) 34.2 

(II) 10.4 

(III) 0.0460 

(IV) 2810

It states that matter can neither be created nor destroyed.

(I) 0.281/5.006=0.0561

(II) 0.58 + 324.65= 325.23

(i) 5.608

(Because the number 8 is more than 5, the digit to be retained 7 is increased by 1)

(ii) 32.39 (Because 2 is less than 5, the digit to be retained 9 is 0)

(iii) 1.790 x 10³ (Because 8 is more than 5, the digit to be retained is increased by 1).

(iv) 0.007837

Answer is Four

 Standard form is 5.608 x 10⁶