Explore topic-wise InterviewSolutions in Current Affairs.

1) An atom with 8 electrons or an octet in their outer most shell is chemically stable or does not combine other atoms. 

Ex : Ne, Ar, etc. 

2) An atom with duplet or 2 electrons in its outer most shell is also more stable when there is only one shell present in it. 

Ex : He 

3) Atoms of an element thus react with other atoms. So as to achieve an octet in their shell. 

4) When elements reacts to form compounds, their atoms must be combining in such a way that they can attain the stable electron distribution of noble gases or inert gases.

The number of electrons or protons in an atom is called the atomic number. It is denoted by Z.

Isotopes of some elements are radioactive. Isotopes are used in various fields such as industry, agriculture, medicine, research field.

1. Isotopes of uranium is used for nuclear fission and production of electricity. 

2. Cobalt – 60 are used in the treatment of cancer. 

3. Iodine – 131 is used in the treatment of goitre. 

4. The radioactive isotopes, Sodium – 24 are used for detection of cracks (leakage) in the underground pipes. 

5. Radioactive isotopes are used for food preservation from microbes. 

6. The radioactive C – 14 is used for determining the age of archaeological objects

The total number of protons and neutrons in the nucleus of the atom is called the atomic mass number. It is denoted by A.

The outermost shell of sodium atom is M shell.

Atomic number (Z): The number of electrons or protons in an atom is called the atomic number. It is denoted by Z.

The outermost shell of hydrogen is K shell.

The substance which reduces the speed of fastmoving neutrons produced in a fission is called a moderator.

Dalton’s atomic theory:

1. According to Dalton’s atomic theory matter is made up of atoms and atoms are indivisible and indestructible. 

2. All atoms of an element are alike while different element have different atom with different mass.

Apsara at Bhabha Atomic Research Centre in Mumbai is the first nuclear reactor in India.

Isotopes of uranium are used as fuel in atomic reactors.

The atom of the element neon has eight electrons in the outermost shell.

(B) Na₂ CO₃ and NaHCO₃ 

Potassium hydrogen carbonate (KHCO₃) is highly water soluble and cannot be precipitated out by reacting with potassium choride (KCl) and hence, potassium carbonate (K₂CO₃) cannot be obtained by Solvay process.

(i) My house is very big. My house has bedrooms, bathrooms, kitchen, prayer room and dining room. I love my house very much. 

(ii) The best thing about my home is that it i feel secure, when i am with my loved ones at my home.We all spend our time together caring and sharing with each other.

(i) A house is made of brick, stone, cement, hard wood, window glass, and a yard. 

(ii) It has eaves, chimneys, tile floors, stucco, roof, and lots of doors. 

(iii) A home is made by family members. 

(iv) It has unselfish acts, sharing, and caring for the loved ones.

The mango tree wanted to drive away the animals because he hated tham. He said that the animals roared loudly and smelled bad.

The mango tree and the banyan tree talked to each other and enjoyed all day long.

1.elephants could fly in the sky like clouds. They could change their shapes. They would fly behind clouds and frighten them. People would look up at the sky and wonder.

2.because there was no electricity, he would get up with the sun, and he would go to bed with the sun, like the birds.

3.like the owl, he could see quite well in the dark. He could tell who was coming by listening to their footsteps.

The other two spectators were a jungle crow and a myna. They had seen them prepare for a fight so ,both of them settled on a cactus to watch the outcome. But they did not just watch. They tried to join the fight by hurling themselves at the cobra.

(i)

(ii): The cobra ,showing his rebellion,hissed and forked his tongue, darting in and out,to show his readiness for fight. It raised three of its six feet off the ground, and spread its broad and spectacled hood. The mongoose bushed his tail. The long hair on his spine stood up.

(i) In the end ,the crow flung nearly twenty feet across the garden, as the cobra's snout hit the crow's body. It fluttered about for a while, then lay still. 

(ii) Myna finally dropped cautiously to the ground, hopped about, peered into the bushes from a safe distance and then with a shrill cry of congratulations, flew away.

Propanol, C₃H₇OH

Answer is (B) -OH

Answer is (B) Phosgene

When silver nitrate solution is added to the given salt solution, if a white curdy precipitate soluble in ammonium hydroxide solution, is formed the presence of a chloride salt can be confirmed.

NaCl + AgNO₃ → AgCl + NaNO₃

Chlorine, liberated when bleaching powder reacts with water, helps disinfection. Bleaching powder is a good source of chlorine.

Circuit will not be completed by using non-metals like sulphur, carbon or iodine because they are bad conductors of electricity. So by packing the powder will not complete the circuit. There is no other by using which we can complete the circuit by using a non-metal.

Chlorine gas reacts with the water to give hydrochloric acid hypochlorous acid (HClO) Cl₂ + H₂O → HCl + HOCl 

Hypochlorous acid decomposes and liberate atomic oxygen. 

HClO → HCl + [O] 

This atomic oxygen oxidises coloured substances.

Bleaching powder is prepared by passing dry chlorine gas over dry slaked lime.

Correct option is C) sulphur

Correct option is B) Sulphur

Yes, when the body has a uniform mass density.

For existence of inverse, function must be one-one and onto.

Clearly, f(-1) = f(1) = 1/2

Hence, f is a many one function.

Therefore f^-1 does not exist.

(a) Virtual and erect 

(b) Virtual and erect; real and inverted

Correct option is D) no unit

Convex mirror has a wider field of view.

A) convex mirror

The assumptions of kinetic theory of gases are:- 

1) A gas consists of a very large number of molecules which should be elastic spheres and identical for a given gas. 

2) The molecules of a gas are in a state of continuous rapid and random motion. 

3) The size of gas molecules is very small as compared to the distance between them. 

4) The molecules do not exert any force of attraction or repulsion on each other. 

5) The collisions of molecules with one another and with walls of the vessel are perfectly elastic.

It is the gas constant per molecule of a gas. If N is Avogadro’s number, then 

k_B = R/N = 1.38 X 10^-23 J/molecule/K

Assumptions of kinetic theory of gases: 

(i) All gases consist of molecules. The molecules are rigid, elastic spheres identical in all respects for a given gas and different for different gases. 

(ii) The size of a molecule is negligible compared with the average distance between two molecules. 

(iii) The molecules are in a state of continuous random motion, moving in all directions with all possible possibilities. 

(iv) During the random motion, the molecules collide with one another and with the walls of the vessel. 

(v) The collisions are perfectly elastic and there are no forces of attraction r repulsion between them 

(vi) Between two collisions, a molecule moves in a straight path with a uniform velocity 

(vii) The collisions are almost instantaneous. 

(viii) The molecular density remains uniform through out the gas.

Answer is (D) x = 0, y = 0

Answer is (A) vector(a perpendicular to b)

The correct option is (B) 3.

3tan θ = 4

tan θ = 4/3

Given expression

= (3sin θ + 2cos θ)/(3sin θ – 2cosθ)

= (3tan θ + 2)/(3tan θ – 2)   [dividing num. and denom. By cos θ]

= (3 x 4/3 + 2)/(3 x 4/3 – 2)

= (4 + 2)/(4 – 2)

= 6/2

= 3

The correct answer is Since 1000g=1kg,therfore,580g=5809/1000kg=5.809kg.

The correct answer is False [14 2/10=14.2]

The correct answer is 2.67