(i) One mole of carbon atom weighs 12 g.Find the mass in grams of one atom of carbon (Given C = 12u, No = 6.022 x 10²³ per mole)
(ii) Calculate the mass of the following:
(a) 0.5 mole of N2 gas
(b) 0.2 mole of O-atoms
(c) 4 moles of aluminium atom
[Given, N = 14 u, 0 = 16 u, Al = 27 u,
Avogadro's number = 6.022 x 10²³ per mole ]

Differentiate between layers and broilers.

(a) What temperature in Kelvin scale is equal to \(50°C\)?
(b) Describe an activity to show that rate of evaporation increases with surface area.
(c) State two differences between evaporation and boiling.

(i) Convert into mole 20 g of water (Atomic mass of hydrogen and oxygen are 1 and 16 respectively).
(ii) Convert into mole 22 g of carbon dioxide.

How will you show that particles of matter have space between them?

What are the characteristics of the particle of matter?

5 g each of nitrogen gas is contained in three vessels A, B, C with volume 1 litre, 1.5 litre and 2.0 litre at the same temperature.How will you measure the volume of the gas in each vessel? Explain.

Liquids generally have lower density as compared to solids.But you must have observed that ice floats on water. Find out why?

How does the b. pt. of a liquid vary with pressure? Explain.

What happens to the kinetic energy of the particles of a liquid when its temperature is raised?State the name and symbol of SI unit of temperature.The boiling point of water is \(100°C\) .Convert this temperature in SI units.

How can the gases be liquefied?

Since early times human beings have been trying to understand their surroundings. As we look our surroundings we have a larger variety of things with different shapes, sizes and textures. Everything in this universe includes the air we breathe, the food we eat or store, clouds, stars, plants, elements, even a drop of water or a particle of water or a particle of sand. We can also see as we look around us that all the things mentioned are either visible or invisible.
(a) What do you call all these materials in one word?
(b) Write at least two characteristics that you can draw from above observation.
(c) In how many forms these materials are available to us?
(d) Can you consider smell or love as materials?
(e) What social consideration can draw from above findings?

What is an atom?

What is meant by the term chemical formula?

Calculate the number of particles in each of the following:
(a) 48 g of Mg
(b) 8 g of O
(c) 0.1 mole of carbon (Atomic mass of Mg = 24u, O=16u., C=12u, Avogadro's number constant N =6.022 x 10²³)

Which has more number of atoms, 100 grams of sodium or 100 grams of iron (Given, atomic mass of Na = 23 u, Fe = 56 u)?

Give the names of the elements present in the following compounds
(a) Quick lime
(b) Hydrogen bromide
(c) Baking powder
(d) Potassium sulphate

The idea of divisibility matter was considered long back in India around 500B.C.An Indian philosopher Maharishi Kanad, postulated that if we go on dividing matter, we shall get smaller and smallest particles beyond which further division will not be possible.Another Indian philosopher Pakudha Katayama elaborated this doctrine and said that these particles normally exist in a combined form and give us various forms of matter which find immense use in our daily life.
(a) Later on what name was given to these indivisible particles by Greek philosopher, Democrities.
(b) What conclusion can you draw from the above paragraph in the social context?

Classify the following in their respective phylum/class:
Jellyfish; Earthworm; Cockroach; Rat

What is community health?

Under which of the following conditions are you most likely to fall sick?
(a) When you are taking examinations
(b) When you have travelled by bus and train for two days.
(c) When your friend suffering from measle.
Why?

How is principle of immunisation implemented for eliminating polio?

What the following things provide us?
Maize, green gram, ground nut and niger.

(i) What are milch animals?
(ii) Give two examples of milch animals.

What are the types of fisheries?

You might have seen that farmers after harvesting,burn dried crop resides Similarly ,gardeners prune and let the cut plant parts dry.Then they burn them in a corner of the park or the park of the garden.The combusion of these dried plant cause air pollution.
On the basis of the above information answer the following questions:
1. What useful products you can obtain from these dead plant parts?
2. How can you prepare that useful product?
3. What is your duty in this regard?