Distance travelled (d) = 400 km
Time taken (t) = 5 hour
Average Speed (s) = \(\frac{d}{t}=\frac{400}{5}=80\) 
Average Speed = 80 kmph (or) Km/hr.

Phenol is a carbolic acid of an organic compound. It is a necessary ingredient for preparing variety of phenol products. The molecular formula of phenol IS C₆H₅ OH, it is a weak acid. It is a volatile, white crystalline powder

We could prepare soft idly as a result of a chemical change named fermentation takes place in the idly batter. During fermentation the idly batter undergoes a chemical change by bacteria. While cooking, the food products undergo so many chemical changes. As a result there are favourable changes in colour, flavour and taste in the food.

i) Free and open software is available at free of cost and can be shared to many end users.
ii) Free software is editable and customizable by the user and this leads to updation or development of new software.
iii) Examples of Free and Open source software are: LINUX, Open office, Geogebra etc.

i) System software (Operating system) is a software that makes the hardware devices process the data fed by the user and to display the result on the output devices like Monitor.
ii) Without the operating system, computer cannot function on its own.
iii) Some of the popular Operating system are linux, MAC OS, Windows.

(i) Two organism depend on one another for their benefits.
(ii) In this process one will not effect another.
(iii) Both organisms are dependent for their food.
(iv) For example the relationship between honey bee and plants.

(i) Learning food chain help us to understand the feeding relationship and interaction between organisms in any ecosystem.
(ii) Understanding the food chain also helps us to appreciate the energy flow and nutrient circulation in an ecosystem.
(iii) The food chain can be used to understand the movement of toxic substances and their impacts.

Cement is manufactured by crushing of naturally occurring minerals such as lime, clay and gypsum.

(i) Create awareness among the people.
(ii) Rain water harvesting.
(iii) Recycling of water by separating pollutants.
(iv) Save water for the future generations by using water carefully and in a limited way, This is conservation of water.
(v) Controlling deforestation.
(vi) Adopting drip irrigation and sprinkler irrigation in agriculture. By this way lesser amount of water can be used for irrigation.

(i) "To a thirsty man, a drop of water is worth more than a sack of gold".
(ii) "Water covers 2/3 of the surface of the earth. But only 0.002% is drinkable".
(iii) "Save water to secure for your future".
(iv) "Store water for dry days".
(v) "Save water, Save life".

(i) Bone provide a frame work for the body.
(ii) Bones along with muscles help in movements such as walking, running chewing and dancing, etc., 

(i) The rib cage is made up of 12 pairs of curved, flat rib bones.
(ii) It protects the delicate vital organs such as heart and lungs.

(i) Cell is the basic structural and functional unit of every living organism.
(ii) cell is self sufficient to carryout all the fundamental and essential functions of an organism.
(iii) Without cell there is no life, So cells are called as building blocks of life.

They are exposed to harsh weather conditions, dust, pollution, heat and cold. So, they can have an adverse effect on their health. Hence, they weak a mask on duty.

During monsoon, the biscuits placed in open lose its crispness. Sugar in biscuits takes up water from the atmosphere and become so soft.

No. Deforestation can be an undesirable change. That is, Deforestation is harmful to our environment and not desired by us.

(i) Burning of paper takes place within a short period of time. So, it is a fast change
(ii) In this process, carbon-di-oxide and water are produced with heat and light energies.

Silver is not used to make electric wires because it is expensive.

No the cell used in the clock cannot give us an electric shock because the voltage is very low in the cell.

The molecules in the solid move faster and vibrate when heating. Spread apart and occupy more space. So solid expands when heated.

Adaptations seen in different types of vertebrates are

Cheese canbe separated from milk by
(i) Filtering the mixture through a fine cloth or strainer.
(ii) The solid particles will be retained by the strainer and unwanted liquid will pass through.

(i) The atoms of a gas never stop moving.
(ii) They are not affected by gravity.
(iii) They spread out in order to occupy the available space.

i) Jasmine plants have weak stems. 
ii) They cannot stand straight on their own.
iii) They must climb on any support to survive.
iv) So jasmine plants are called twiners.

Magnets lose their properties if they are heated or dropped from a height or hit with a hammer.

Palm tree is monocot plant.Always monocat trees give only softwood.So we can't get hardwood from palm trees. 

(i) Dengue and Malaria will spread by mosquitoes.
(ii) If the waste is increase leads to occumulation of water can able to growth of mosquito and can cause diseases.

Bio waste to compost preparation:
Step (i) : Acquire a bin.
Wooden bins or small pits are taken for the process.
Step (ii) : Prepare the bedding.
Soil or moist news papers are used as a bed.
Step (iii) : Add the worms.
Spread the worms on the bedding with moist newspaper.
Step (iv) : Bury food scraps under bedding.
Feed the worms with fruit and vegetable scraps.
Step (v) : Place a full sheet of dry newspaper on the top of the bedding.
Replace this sheet frequently.
Step (vi) : Choose a cover for the bin.
Cover the bin with a lid for about, 3-4 weeks with proper air contact.
Benefits of Vermi castings:
(i) Adds organic matter to the soil.
(ii) Soil absorbtion and retentivity of water is increased.
(iii) Helps to form soil aggregates.
(iv) Ease cultivation.

If we keep a strong bar magnet above the glass of water, all pins inside the water will come up due to its attraction towards the magnet.