Explore topic-wise InterviewSolutions in .

The moment he is out of the ship, there is no external force on the astronaut. We are assuming that, there are no nearly stars or their satellites to exert gravitational force on him, and the small spaceship exerts negligible gravitational attraction on him. By the first law of motion, the acceleration of the astronaut is zero.

Conversion : We know that

1 light year = 9.46 × 10¹⁵ m

∴ 4.29 light years = 4.29 × 9.46 × 10¹⁵

= 4.058 × 10¹⁶ m

Also, 1 parsec = 3.08 × 10¹⁶ m

∴ 4.29 light year = \(\frac{4.058\times10^{16}}{3.08\times10^{16}}\)

= 1.318 parsec

= 1.32 parsec

(b) Parallax− In six months, the distance between two observations will be equal to the diameter of the orbit, i.e.

2 × radius of orbit

2 AU = 2 × 1.496 × 10¹¹ m

Using, θ = \(\frac{b}{D}\)

where b = 2 × 1.496 × 10¹¹ m

and D = 4.058 × 10¹⁶

we get, θ = \(\frac{2\times1.496\times10^{11}}{4.058\times10^{16}}\)

= 7.37 × 10^-6 rad

= 7.37 × 10^-6 × \(\frac{180\times60\times60}{\pi}\)

= 1.52 second of arc.

Distance of Alpha Centauri from the Earth = 4.29 ly

= 4.29 × 365 × 24 v 3600 × 3 × 10⁸ = 4.06 × 10¹⁶m

1 parsec = 3.084 × 10¹⁶ m

∴ Distance = ((4.06 x 10¹⁶)/(3.084 x 10¹⁶)) = 1.32parsec.

D = b/θ

b = 3 × 10⁴, D = 4.06 × 10¹⁶ m

Parallax θ = 2 × D = 2.64

(b) Sound waves are longitudinal while light rays are transverse
Diffraction effect is more pronounced if the size of obstacle or aperture is of the order of the wavelength of the waves. As the wavelength of light (~ 10^-6 m) is much smaller than the size of the objects around us, so diffraction of light is not easily seen. But sound waves have large wavelength. They get easily diffracted by the objects around us.

The answer is (b)

Diffraction pattern must be broader than width of the slit.

The resolving power of a microscope is defined as reciprocal of the smallest distance between two point objects at which they can be just resolved when seen through the microscope.
R.P. of a microscope = \(\frac{1}{d}=\frac{2 n \sin \theta}{\lambda}\)
(i) As R.P. ∝ \(\frac{1}{\lambda}\)
When λ decreases, R.P. increases.
(ii) When the aperture of the objective lens decreases, the semivertical angle θ decreases and hence the resolving power of the microscope increases.

(d) tan^-1(n)
From Brewster’s law
n = tan i_p ⇒ tan^-1(n)

Angular separation θ ∝ \(\frac{1}{D}\), when D becomes twice, then θ remains half.

(a), (b)

(a) a larger angle to be subtended by the object at the eye and hence viewed in greater detail. 

(b) the formation of a virtual erect image. 

Acoording to the law of conservation of mass, the mass of products formed are equal to the mass of reactants consumed. Hence, the mass of salt and water formed is equal to the combined mass of magnesium hydroxide Mg (OH)₂ and HCl.

Correct option is A) valency

The correct answer is : (c) 2.5g and 1.1g

We have only 26 alphabets in English, but there are over 100 known elements. We cannot write the same symbol for carbon, calcium, chromium, etc.

Correct option is: A) weak acid

Correct option is: A) 5-10%

Vinegar with chemical formula CH₃COOH is used as preservative. 5-8% of solution of acetic acid or ethanoic acid in water is called vinegar and it is used widely as preservative in pickles.

1. Dilute acetic acid is used as a food preservative in the preparation of pickles and sauces.

2. As vinegar, it is also used as an appetiser for dressing food dishes.

The compound is ethanoic acid also known as acetic acid (CH₃COOH). It is a weak organic acid. CH₃COOH reacts with carbonates and bicarbonates to release CO₂ which is a colourless gas.

The reactions involved are:

2CH₃COOH + Na₂CO₃→ 2CH₃COONa + CO₂↑ + H₂O 

CH₃COOH + NaHCO₃→ CH₃COONa + CO₂↑ + H₂O

Correct option is  D) Ester

B. Square planar

(4) quadratic

f(x) = (x + 1)³ – (x – 1)³ 

= x³ + 3x² + 3x + 1 - [x³ – 3x² + 3x – 1]

= x³ + 3x² + 3x + 1 – x³ + 3x² – 3x + 1 = 6x² + 2 

It is a quadratic function.

Correct option is  A) 5 -10 %

Correct option is  A) weak acid

Correct Answer is: B. Square planar 

The VSEPR structure of XeF₄ is square planar. It is an octahedral but because of the lone pairs, it dictates there 6 Domains around the central atom and the VSEPR theory states any AX4E₂ specie with 2 lone pairs is square planar.

Many years before the stranger was helped by the gentleman.

1.→F.

2.→F.

3.→F.

4.→F.

5.→T.

6.→F.

7.→F.

8.→T.

9.→T.

10.→T.

The gentleman took every care of the guests who had come on his birthday.In the evening he gave them a grand feast. He did everything as his duty.

अपने जन्मदिन के मौके पर आए अतिथियों का भले आदमी ने हर प्रकार से खयाल रखा। शाम के समय उन्हे एक जबरदस्त प्रीतिभोज दिया गया। उन्होंने वह सब किया जो वह अपना कर्त्तव्य समझते थे।

When the gentleman was putting away the gifts, he suddenly noticed the shadow of a man’s head on the floor of the hall. He thought that someone was hiding in the roof.

जब वह भला आदमी अपने जन्मदिन पर आए तौ को समेट कर रख रहा था तो अचानक उसने अपने घर के बड़े कमरे की छत पर किसी आदमी के सिर का छाया महशूश किया। उसने सोचा कि कोई व्यक्ति उसके घर के छत पर छिपा हुआ है।

The gentleman was a kind man who thought that a bag of coins might help him fight his problems.

भला आदमी एक दयालु व्यक्ति था जिसने यह सोचा कि सिक्कों से भरा थैला संभवतः उस चोर को अपनी समस्याओं से लड़ने में मदद करेगा और वह चोरी जैसे गलत रास्ते से हट कर जीवन में कुछ अच्छ काम करेगा।

The thief was treated with kindness and with the same honor as was given to the other guests. He himself offered humble meal to the thief and he himself took him to the gate of the courtyard.

चोर के साथ भी भले आदमी ने अत्यंत ही भद्रता तथा दयालुता के साथ व्यवहार किया जैसा कि उसने अपने अन्य अतिथियों के साथ किया था। उसने चोर को अपने हाथों से स्वादिश्ट भोजन उसे कराया, उपहार दिया और सिक्कों से भरा एक थैला भी भेट किया तथा अपने से घर के दरवाजे पर आकर उसे छोड़ गया।

The kindness shown by the gentleman totally changed the life of the stranger. He gave up the evil ways of life and tried to earn livelihood by honest means. As the years rolled by, he gathered lots of money and became rich and had never changed his behavior. He was always kind to other people and showed the same kindness as he had received from the gentleman.

भले आदमी के द्वारा दिखाए गए दयालुता ने उस चोर की जिंदगी को पूरी तरह से बदल दिया। उसने जीवन के बुरे रास्ते को छोड़ दिया और ईमानदारी पूर्वक मेहनत से काम कर अपना आजीविका चलाने लगा। जैसे-जैसे साल दर साल गुजरता गया, उसने कही पैसा कमा लिया और वह भी एक धनी आदमी बन गया लेकिन उसने अपने व्यवहार को कभी नहीं बदला। वह हमेशा उसी प्रकार की दयालुता दूसरे व्यक्ति के प्रति रखता जिस प्रकार की दयालुता उस भद्र पुरुष ने उसके साथ किया था।

The stranger’s story was pathetic.

In the story, A Man’s True Son many years ago the stranger was the uninvited guest. He had entered the gentleman’ house to commit theft who found him hiding in the roof. When all the guests had gone, he called the thief and served him food. He also gave him a gift and bag of coins. The thief gave up the evil ways of life and worked hard to earn his livelihood by honest means. Gradually he became rich but he was never arrogant to the other people. He showed same kindness which he had received from the gentleman. Hence the other act of kindness was born and the stranger proved himself to be a true son.

एक मनुष्य का सच्चा बेटा कहानी में कई साल पहले वह अजनबी व्यक्ति एक बिना बुलाया मेहमान था। वह उसे भले आदमी के घर में चोरी करने के इरादे से घुसा था जिसे उसने छत पर छिपा हुआ देखा। जब सारे मेहमान खा कर चले गए तब उस भले आदमी ने उस चोर को नीचे बुलाया और अपने हाथों से खाना परोस कर खिलाया। उसने उसे सिक्कों से भरा एक थैला और उपहार भी दिया।

इस घटना के बाद उस चोर ने अपने बुरे कमों को सदा के लिए छोड़ दिया और जीवन को एक नई दिशा दे दी। वह ईमानदारी पूर्वक मेहनत से काम करने लगा। जल्दी ही वह एक धनी व्यक्ति बन गया लेकिन वह कभी दूसरों के प्रति अहंकारी व्यक्ति नहीं बना। वह सदा दूसरों के प्रति वही भद्रता और दयालुता का व्यवहार करता जैसा व्यवहार उस भले आदमी ने उसके साथ किया था। इस प्रकार से एक। नई दयालुता का जन्म हुआ और उस अजनबी व्यक्ति ने साबित कर दिया कि वह उस भले आदमी का सच्चा बेटा है।

Correct answer is (d) abuses

(ii) High negative standard electrode potential

(iv) Large atomic size

The gentleman was kind to the thief. He himself offered him humble meal and gave him gifts and a bag of coins. The thief forgot his evil ways of life. He worked hard and became a rich man. Although he was a rich man, he was never arrogant to the other human beings. He often showed the same kindness which the gentleman had shown to him. So the stranger or thief has extended the lesson of kindness in the present story.

भला आदमी उस चोर के प्रति दयालु था। उसने उसे । अपने हाथों से स्वादिश्ट भोजन कराया और उपहार तथा सिक्कों से भरा एक थैला भी दिया। चोर ने अपने जीवन के बुरे कामों को छोड़ दिया। वह कठोर मेहनत करने लगा और समय के साथ एक धनवान व्यक्ति भी बन गया। जबकि वह एक धनवान व्यक्ति बन गया था कर भी वह अन्य किसी भी व्यक्ति के प्रति घमंडी नहीं हुआ। वह भी उसी प्रकार की दयालुता दूसरों के साथ दिखाता जिस प्रकार की दयालुता उसके साथ उस भले आदमी ने दिखाया था। इस तरह से उस अजनबी व्यक्ति अर्थात चोर ने इस कहानी में दयालुता को आगे भी बढ़ाने का काम किया।

(a) If both assertion and reason are true and reason is the true explanation of the assertion.

Graphite is thermodynamically most stable allotrope of carbon.

The presence of hydrogen bonds makes it polymeric.

It accepts a pair of electrons from OH^- ion of H₂O therefore, it is monobasic acid.

 Hybridisation changes from sp² to sp³

The reactions in which an element undergoes simultaneously both oxidation and reduction are called as disproportionation reactions. 

Example: 

P₄ + 3NaOH + 3H₂O → PH₃ + 3NaH₂PO₂ 

2HCHO + H₂O → CH₃OH + HCOOH

(d) AgCl + NH_{3 \(\rightarrow\)} [Ag(NH₃)₂]Cl

(c) Sublimation of iodine

Sublimation of iodine I_2(s) ⇌ I_2(g) is an example of physical equilibrium, whereas a, b and dare examples of chemical equilibrium.

(d) 4H₃PO₃ → 3H₃PO₄ + PH₃

4H₃PO₃ → 3H₃PO₄ + PH₃ (Auto oxidation and reduction reaction)

Fullerenes are bucky balls with 60-120 carbon atoms. They are soccer like with pentagonal and hexagonal like.

i. Fullerenes are allotropes of carbon in which carbon molecules are linked by a definite numbers of carbon atoms, for example as in C₆₀ .

ii. Fullerenes are produced when an electric arc is struck between the graphite electrodes in an inert atmosphere of argon or helium. The soot formed contains significant amount of C₆₀ fullerene and smaller amounts of other fullerenes C₃₂ , C₅₀ , C₇₀ and C₈₄ .

Fullerenes are the allotropes of carbon. Its structure is like a soccer ball .They is prepared by heating graphite in electric arc in presence of inert gases such as helium or argon.

(a) it is due to decrease in bond dissociation energy which is due to increase in atomic size 

C-C > Si-Si >Ge-Ge>Sn-Sn>Pb-Pb. 

(b)- It is due to inert pair effect. 

(c)- Molten AlBr₃ is poor conductor of electricity because it is covalent compound. 

K₁ and K₂ are velocity constant o forward and backward reactions. The equilibrium constant K_C of the reaction is K₁ / K₂ .