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A sample of water under study was found to boil at 102°C at normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment.

The boiling point of pure water is 100°C at 1atm. The freezing point of pure water is O°C. The sample... View Article

In human females, each time during maturation and release of the egg the inner wall of the uterus thickens. Is this thickening permanent? Give reasons.

The thickening of the inner wall of the uterus is not permanent. It is built up after the release of... View Article

Which of the following is a pair of exhaustible natural resources? (a) coal and soil (b) air and sun-light (c) water and petroleum (d) wildlife and minerals

Wildlife and minerals are exhaustible natural resources, as they are present in limited quantity in nature and can be exhausted... View Article

Materials which can be drawn into wires are called ductile. Which of the following is not a ductile material? (a) Silver (b) Copper (c) Sulphur (d) Aluminium

(c) Sulphur Materials which can be drawn into wires are called ductile. Sulphur is brittle. We cannot obtain thin sheets... View Article

Name the target organs for the following diseases (a) Hepatitis targets. (b) Fits or unconsciousness targets . (c) Pneumonia targets . (d) Fungal disease targets .

(a) Liver Hepatitis causes scarring of the liver (cirrhosis). (b) Brain A seizure, also known as a fit, is caused... View Article

You are provided with a mixture of naphthalene and ammonium chloride by your teacher. Suggest an activity to separate them with well-labelled diagram.

Naphthalene is insoluble in water but soluble in ether an organic solvent. It is volatile at room temperature Ammonium chloride... View Article

Which of the following feature will help you in distinguishing a plant cell from an animal cell? (a) cell wall (b) cell membrane (c) mitochondria (d) nucleus

a) Cell wall The cell is the fundamental unit of life. All the life activities are carried out by cells.... View Article

In coastal area, wind current moves from the sea towards the land during the day; but during the night it moves from land to the sea. Discuss the reason.

In coastal areas, during daytime, there is a regular flow of cool air from the sea towards the land. At... View Article

Which of the following is a recently originated problem of environment? (a) Ozone layer depletion (b) Greenhouse effect (c) Global warming (d) All of the above

d) All of these Explanation Ozone layer depletion The ozone layer is a region in the earth’s stratosphere that contains... View Article

Increased concentration of nitrogen in the air is believed to cause global warming. (True or False). Also write the false statements in their correct form.

False. An increase in the CO2 in the air is the cause of global warming. There are various causes of... View Article

The main function of abscisic acid in plants is to (a) increase the length of cells (b) promote cell division (c) inhibit growth (d) promote the growth of stem

c) Inhibit growth Explanation Abscisic acid (ABA) is a plant hormone. ABA capacities in many plant formative cycles, including seed... View Article

A synthetic fibre which looks like silk is obtained by chemical treatment of wood pulp. It is, therefore, known as artificial silk. What is its common name?

Rayon is obtained by the chemical treatment of wood pulp or cellulose. A synthetic fibre that looks like silk is... View Article

Classify the following crops into Kharif and Rabi crops and write in the tabular column given below: Maize, paddy, mustard, pea, gram, wheat, groundnut, cotton.

Kharif: Maize, paddy, groundnut, cottonRabi : Mustard, pea, wheat, gram Kharif crops The crops that are sown in the rainy... View Article

Two green plants are kept separately in oxygen-free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.

The plant which is kept in continuous light will live longer. We know that plant release carbon dioxide during respiration.... View Article

Which of the following are Indian cattle? (i) Bos indicus (ii) Bos domestica (iii) Bos bubalis (iv) Bos vulgaris (a) (i) and (iii) (b) (i) and (ii) (c) (ii) and (iii) (d) (iii) and (iv)

The correct option is – a) (i) and (iii) Explanation Bos indicus and Bos bubalis are Indian cattle. Bos bubalis or... View Article

Select the articles from the following list which are biodegradable. (a) Paper (b) Woollen clothes (c) Wood (d) Aluminium can (e) Plastic bag (f) Peels of vegetables

The list of biodegradable articles is mentioned below – (a) paper (b) woolen clothes (c) wood (f) peels of vegetables.... View Article

Which of the following groups contain all synthetic substances? (a) Nylon, Terylene, Wool (b) Cotton, Polycot, Rayon (c) PVC, Polythene, Bakelite (d) Acrylic, Silk, Wool

(c) PVC, Polythene, Bakelite Synthetic materials are made by chemically changing the starting substances to create a material with different... View Article

Given below are statements about the harmful effects of weeds on crop plants. (i) They interfere with harvesting. (ii) They help crop plants to grow healthily. (iii) They compete with crop plants for water, nutrients, space and light. (iv) They affect plant growth. Choose the correct combination of statements. (a) i, iii, iv (b) iii only (c) iii, iv (d) i, ii, iii, iv

(a) i, iii, iv Explanation Harmful effects of weeds on crop of plant are as follows: They interfere in harvesting.... View Article

Given below is a conversation between two farmers Heera and Beera. Heera: Brother Beera, your maize crops looks beautiful! They have grown pretty fast. Beera: Yes, I have sprayed urea this time. What about you? Heera: Well, I am still relying on good old cow dung. I am saving money on buying a tractor. Beera: That’s good. Tractor saves a lot of time and labour. Heera: Yes, it’s been very labour intensive for me and now these weeds have come up. Beera: Try weedicides, they are very effective. Now answer the following questions. a) List the practices which are not environment-friendly and why? b) What is the advantage of modern agriculture implements over traditional ones? c) Name one weedicide and the precaution farmers must take during its application.

a) The use of chemical fertilizers, insecticides, pesticides, weedicides are not environment-friendly as they contain chemicals which are very harmful... View Article

The calorific value of a fuel is expressed in a unit called (a) kilojoule per litre (b) kilogram per millilitre (c) kilojoule per gram (d) kilojoule per kilogram

The calorific value of a fuel is expressed in a unit called kilojoule per kilogram. Calorific value is the amount... View Article

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