Describe the process of neutralisation with the help of an example.
NEUTRALISATION: When an acid is mixed with a base, they neutralise the effect of each other. The products formed on mixing an acid and a base are salt and water. The reaction between acid and base which produces salt and water with the evolution or release of heat is known as neutralization reaction.
Acid + Base → Salt + Water + Heat (released)
In a neutralisation reaction, salt are formed which is neutral by nature. The salt formed during a neutralisation reaction depends on which acid and which base are reacted with each other. For example: Sodium hydroxide is a base and hydrochloric acid is an acid. So, when sodium hydroxide is treated with hydrochloric acid, then a neutralisation reaction takes place to form sodium chloride (salt) and water.
Sodium hydroxide + Hydrochloric acid → Sodium chloride + Water
(NaOH) (HCl) (NaCl) (H2O)
The salt formed in this neutralisation reaction of sodium hydroxide and hydrochloric acid is sodium chloride (NaCl). It is known as common salt.
Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food
Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down Across
(D) 1 : Thorough washing (A) 1 : Keeps warm
2 : Animal fibre 2 : Its leaves are eaten by silkworms
3 : Long thread like structure 3 : Hatches from egg of moth
Sketch the cross section of soil and label the various layers.
Take three test-tubes. Fill æth of each with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2?
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Here is a crossword puzzle: Good luck!
Across
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body
Down
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which causes cholera
7. A chemical to disinfect water
Match the items in Column I with those in Column II:
Column I Column II
(i) A home for living organisms (a) Large particles
(ii) Upper layer of the soil (b) All kinds of soil
(iii) Sandy soil (c) Dark in colour
(iv) Middle layer of the soil (d) Small particles and packed tight (v) Clayey soil (e) Lesser amount of humus
Write one similarity and one difference between the nutrition in amoeba and human beings.
An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both.
Why does an athlete breathe faster and deeper than usual after finishing the race?
How does the process of fertilisation take place in flowers?
Describe how crystals of copper sulphate are prepared.
What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture
Which features adapt polar bears to live in extremely cold climate?
(i) A white fur, fat below skin, keen sense of smell.
(ii) Thin skin, large eyes, a white fur.
(iii) A long tail, strong claws, white large paws.
(iv) White body, paws for swimming, gills for respiration.
In Fig. 17.15, the artist has forgotten to put the labels and directions on the arrows. Mark the directions on the arrows and label the diagram using the following labels:
clouds, rain, atmosphere, carbon dioxide, oxygen, plants, animals, soil, roots, water table.
Following are some of the characteristics of animals:
(i) Diets heavy on fruits (ii) White fur
(iii) Need to migrate (iv) Loud voice
(v) Sticky pads on feet (vi) Layer of fat under skin
(vii) Wide and large paws (viii) Bright colours
(ix) Strong tails (x) Long and large beak
For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions?
Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
(iii) The pores through which leaves exchange gases.
Label Fig. 2.11 of the digestive system.
Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.
Fill in the blanks:
(a) An image that cannot be obtained on a screen is called ____________.
(b) Image formed by a convex __________ is always virtual and smaller in size.
(c) An image formed by a __________ mirror is always of the same size as that of the object.
(d) An image which can be obtained on a screen is called a _________ image.
(e) An image formed by a concave ___________ cannot be obtained on a screen.