10th Physical Science Important Questions and Answers for Public Exams

Q: What is the action of soap particles on greasy cloth? (4 Marks)

A: Soaps and detergents make oil and dirt present on the cloth come out into water, there by making the cloth clean. Soap has one polar end and one nonpolar end. The polar end is hydrophilic in nature and this end is attracted towards water.

The non-polar end is hydrophobic, in nature and it is attracted towards grease or oil on the cloth, but not attracted towards water. When soap is dissolved in water, its hydrophobic ends attach themselves to dirt and remove it from the cloth. The hydrophobic end of the soap molecules move towards the dirt or grease particles.

The hydrophobic ends attached to the dirt particle and try to pull out. The molecules of soap surround the dirt particle at the centre of the cluster and form a spherical structure called micelle. These micelles remain suspended in water like particles in a collidal solution. The various micelles present in water do not come together to form a precipitate as each micelle repells the other because of the ionion repulsion. Thus, the dust particles remain trapped in micelles and are easily rinsed away with water. Hence, soap micelles remove dirt by dissolving in water.

Q: We know metals are arranged basing on their reactivity. What is the name given to that arrangement? How it helps in extraction of metals? (4 Marks)

A: Activity Series: Extraction of the metal from its ore depends on the reactivity of the metal. To understand the order of reactivity of metals

that are very familiar, we study their chemical reactions with cold water, steam, dilute, strong acids and Cl2 and based on their vigorous activity order in these reactions, we frame out activity series.

Arrangement of the metals in decreasing order of their reactivity is known as activity series. Usefulness of activity series in extraction of metals: Simple chemical reduction methods like heating with C, Co etc to reduce the ores of these metals depends mainly on the position of the metal in the activity series. Extration of metals at the top of the activity series can be done by electrolysis. Extraction of metals in the middle of the activity series can be extracted by 

a) Sulphide ores are converted into oxides by roasting.

b) The metal oxides are then reduced to the corresponding metal by using suitable reducing agents like carbon. Extraction of metals at the bottom of the acitivity series by heating alone as they are often found in free state.

Extraction of these metals can also be done by displacement from aqueous solutions.

Q: How do you appreciate the role of Buckminister fullerence in medicine. (2 Marks)

A: Fullerences are under study for potential medicinal use such as specific antibiotics to target resistant bacteria and even target certain cancer cells such as melonoma. This is still under research studies.

I appreciate its usefulness in medicine which may become a good medicine for curing certain cancer in the time to come.

Q: What is the role of esters in everyday life? (2 Marks)

A: Esters are generally volatile liquids with sweet or pleasent smell or fruity smell. Artificial perfumes are made with esters. Esters are used as flavouring agents. Esters are used in making artificial flavours and essences used in ice-creams, sweets, cool drinks... etc. Saponification (soap making) is the alkaline hydrolysis of esters.

SSC Public Exams English Comprehension - Familiar Passage

1. The potter walked through the wet forest

A) in search of a tiger.

B) to beat the tiger.

C) to look for his wife.

D) in search of his donkey.

2. He muttered to himself that

A) he would tie the tiger up under the tree all night.

B) he would beat the donkey.

C) he would tie the donkey up under the tree all night.

D) he would sleep under the tree the whole night.

3. The potter said that he had done nothing of the sort. What was it?

A) catching the donkey.

B) catching the tiger.

C) bringing his donkey home.

D) his sleeping under the tree.

4. 'He then jumped on to the frightened animal's back!. which was the frightened animal? Why was it frightened?

5. Why did the villagers praise and thank the potter?

Answers: 1-D; 2-C; 3-B.

4. The frightened animal was the tiger. The tiger was frightened as it thought that the creature that was beating and kicking it was 'leak' which it thought was a very dangerous creature.

5. The villagers praised the potter for his courage in catching the tiger. They thanked him because the tiger had eaten many of their goats and buffaloes.

10th Class Public Exams Reading Comprehension Tips - Unfamiliar Passage

Comprehension passages are intended to test and improve one's ability to read and understand the language. The passages given for reading comprehension are i) Familiar (From Text Book) and ii) Unfamiliar (general passages).

Tips to follow: To comprehend means to understand. In order to answer the given question, you have to read till you come to have a general idea of the passage, step by step. Read the passage carefully to know what the passage is about. Once you identify the main points you can answer any question efficiently.

Identify, analyse, interpret and then infer the ideas in the text given. You have to deduce the meaning of unfamiliar words, then only you can answer the questions ably.

1. What is the passage about?

A) A town in the heart of America.

B) The unexplainable deaths of birds, animals and people.

C) Total environmental disaster caused by man.

D) The deserted feeding stations in the backyard.

2. Why were the apple trees not bearing fruit?

A) There was no water.

B) There were no trees.

C) There was no pollination.

D) There were no people to nurture.

3. The writer says that it was a spring without voices because ....

A) There were no bees and birds.

B) There were no trees.

C) Fire destroyed the vegetation.

D) There were no living beings.

4. The expression 'had silenced the rebirth of new life...' means

A) The possibility of new life had been taken away.

B) Animals and birds had been made silent.

C) Life on earth had been endangered.

D) There had been drastic changes in the seasons.

Answer the following questions in two or three sentences each.

5. Why does the writer say that there was a shadow of death?

6. What, according to you, is the white granular powder?

7. The writer says 'People themselves are responsible for the disaster'. Cite one example of the disastrous action done by the people.

Answers: 1-C; 2-C; 3-D; 4-A.

5. The writer says that there was a shadow of death as mysterious maladies swept the blocks of chickens. The cattle and sheep sickened and died. There had been several sudden and unexplained deaths of both adults and children.

6. The white granular powder is nothing but the harmful chemical remains.

7. Uncontrolled use of pesticides leads to other problems. We have to eat the vegetables, fruits and other food items which are filled with chemicals and this leads to health problems. Another example is using the atomic

weapons and destroying our fellow countries.