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1. Bases are bitter to taste. 

2. They are slippery to touch. 

3. They turn red litmus to blue colour, methyl orange to yellow colour, phenolphtha- lein to pink and hibiscus indicator to green colour. 

4. They change the colour of turmeric indicator to reddish brown. 

5. pH of acids is more than 7. 

6. Bases like sodium hydroxide react with metals and releases hydrogen gas. 

7. Bases react with acid to form water and salt. This reaction is called neutralisation reaction. 

8. Sodium hydroxide, magnesium hydroxide, potassium hydroxide and calcium hy-droxide are examples for bases.

• Bases are used in making soaps and cleaning substances.
• Soap will be prepared by adding fatty acids to alkalies.

When carbon dioxide is added to water, it become carbonic acid/soda.

Bath soap is prepared using potassium hydroxide.

The correct answer is C) more than 7.

(a) To draw water ‘from a well, we have to apply pull force at the rope. To draw an object by applying force

(b) If the two forces applied to an object are equal and act in opposite directions, the net force acting on the object will be zero. 

The force applied on the body are equal and opposite direction, force cancel out and net force is zero.

(c) Force could be a push or a pull. A push or pull on an object is known as force.

(d) Force has magnitude as well as direction. Force is a vector quantity and it depends on direction.

(e) A force arises due to interaction between two objects. The interaction between two objects due to a force .

(f) A charged body attracts an uncharged body towards it. Force attracts to each other of two objects when they are unlike charges.

(g) The north pole of a magnet repeals the north pole of another magnet. Like poles of magnet repeal to each other’s.

(h) Force acting on a unit area is called Pressure.

(i) The pressure exerted by a liquid increases with depth. Pressure = height × density of object × gravity

(J) A drinking straw works on the existence of atmospheric pressure. The level of water rises from drinking straw due to atmospheric pressure.

(k) Atmospheric pressure decreases with increasing height. Pressure is inversely proportional to height

(a) Convex mirror.

(b) Concave mirror

Convex mirror (since focal length is positive).

Bases are slippery to touch.

D. B and D 

P = F/A

(a) True Pressure depends on the area and force.

(b) False Pressure depends on the area and force.

Given: Force applied is given as: 200 N

Now, we know that the Pressure is the force applied perpendicular to the surface of an object per unit area. or Pressure = Force/ Area

(a) Area = 10m²

P = 200N/10m² 

or P = 20 Nm² or 20 Pascal

(b) Area = 10m2

P = 200N/5m² 

or P = 40 Nm² or 40 Pascal

Lemon juice is another substance which has sour taste like tamarind.

1. Substance that is slippery to touch and bitter in taste is Base. 

2. Substance that is sour in taste is Acid. 

3. When acids react with base neutralisation reaction takes place. 

4. Salt and water will form in neutralisation reaction. Acid + Base → Salt + Water

Our Blood (Internal body pressure created by blood)

Electrostatic force due to create unlike charge by rubbing to get attracted

D. gravitational force 

Force applied when it is in non contact with the object.

Because the atmosphere also pressurize the body. Diving down 100 meters will pressurize the gasses in the body and they will compress, like the air in our lungs and if the lung volume gets below half a litre the lungs can get partly filled with blood plasma. But sorry no bone crushing. But if you take a big breath and hold it while you ascend from 100 meters to the surface, your ribs may start to break.

The substance which is neither an acid nor a base is known as neutral substance. Pure water is a neutral substance.

This sentence was said by the girl (selling baskets) to the author.

Electrostatic force:

 The force acting on object due to its charged.

Acids:

Vinegar, lemon juice, tomato juice, bathroom cleaner (hydrochloric acid), cool drinks, curd, etc.

Bases :

Bath soap, cloth soap, baking soda, tooth paste, dish wash liquid etc.

Neutral: 

Water

There are two eclipses:

1. Solar eclipse 

2. Lunar eclipse

1. Solar eclipse:

There are two types of Solar eclipse, (a) Total solar eclipse (b) Partial solar eclipse

a. Total solar eclipse: In total solar eclipse, the moon is between the sun and the earth and the moon shadow covers the sun disc fully by perfect alignment. The part of the earth that lies in the umbra of the moon experiences total solar eclipse.

b. Partial solar eclipse: In partial solar eclipse, the moon is between the sun and the earth arid the moon shadow does not cover the sun disc fully, because of imperfect alignment. The part of the earth that lies in the penumbra of the moon experiences partial solar eclipse.

c. The solar eclipse occur on a new moon day.

d. Solar eclipse last for few minutes.

2. Lunar eclipse:

There are two types of Lunar eclipse, (a) Total lunar eclipse (b) Partial lunar eclipse

a. Total lunar eclipse: In total lunar eclipse, the earth comes in between the sun and the moon and the earth’s shadow covers the moon’s surface fully because of perfect alignment.

b. Partial lunar eclipse: In partial lunar eclipse, the earth’s shadow does not cover the moon’s surface fully because of inperfect alignment. A small part of the moon’s surface is covered by umbra part of earth’s shadow.

c. The lunar eclipse occurs on a full moon night.

d. Lunar eclipse last for few hours.

Solar, lunar eclipse have been traditionally observed as an ominous sign and therefore superstitions are prevalent in association with these natural phenomena.

1. All these misconceptions should be removed by explaining scientifically the process of eclipse how it happens: 

(a) Explain with the help of diagram and models of sun, moon and earth, 

(b) Explain how special glasses which will protect us from UV rays, and excess heat can be used to observe eclipses safely.

2. Also inform that eclipses are natural phenomena and can be predicted in advance.

i. umbra, penumbra

ii. earth, moon

iii. moon, earth

iv. scattering of light

1. The day on which the sun reaches exactly overhead is called zero shadow day.

2. On this day, at noon, shadow completely disappears. 

3. This event can be seen in the region between the Tropic of Cancer (23.5°N) and at tropic of Capricon (23.5°S). 

4. The shadow diminishes and eventually disappears for a while only to reappear later 

5. This phenomenon occurs twice every year Mumbai got to witness it on May 14, 2018 last year.

• A – Solar B – Lunar
• C – Total Solar 
• D – Partial Solar 
• E – Total Lunar 
• F – Partial Lunar
• G – Moon is not in a straight line between earth and sun 
• H – It is in the penumbra region of the moon 
• I – The earth comes in between the sun and moon and they are not in a straight line.

1. As more and more milk is added, more particles of protein and fat scatter the light and the blue colour is scattered more and more than orange and red light and the beam appears blue from the sides.

2. If few drops of milk are added, along with blue colour, orange and yellow also are scattered and only the intense red is seen from the front. 

3. But when many more drops are added, even the red colour is scattered and we do not see any colour from the front.

1. The formation of rainbow, shift in position of stars, increased day time, mirage, inverted image, glittering of diamond, the working of lens and prism, bending of pen in water are examples of scattering of light.

2. The blue colour of the sky is due to the scattering of sunlight by the molecules of air.

3. During sunrise and sunset, sunlight has to travel greater distance, so shorter wavelength gets scattered off and removed and only orange and red with longer wavelengths reach us.

4. So during sunrise and sunset, sky appears fed and orange.

1. Yes, the day on which the sun reaches exactly overhead, at noon, shadow completely disappears. ‘This event can be seen in the region between the Tropic of Cancer (23.5°N) and Tropic of Capricorn (23.5°S).

2. The shadow diminishes and eventually disappears for a while only to reappear later.

As seen from the earth, when a planet or a star passes behind the moon, that state is called an Occultation.

1. During a solar eclipse ultra-violet rays which are harmful to us reach the earth and may lead to eclipse blindness or retinal bums and cataracts.

2. In order to protect our eyes a solar eclipse should never be watched with the naked eye.

3. A special type of goggles should be used for this.

1. When the moon comes in between the sun and the earth and the solar disc is corripletely covered by the moon, it is called total solar eclipse.

2. When the solar disc is not covered fully by the moon, it is partial solar eclipse.

1. The umbra, penumbra are the distinct parts of a shadow, created by any light source after striking on an opaque object.

2. For a point source, only the umbra is cast sharp dark shadow and not penumbra, because all the light of the point source will be blocked by any shadowing object.

3. Whereas penumbra forms only when some of the light from the source gets blocked by the shadowing object and not all of it does.

1. Scattering of light is the deviation of light rays from its straight path. 

2. As light propagates through the atmosphere, it travels in a straight path until it is obstructed by bits of dust or gas molecules in the atmosphere 

3. The process in which light gets deflected by the particles in the medium through which the light passes is called scattering, e.g. The blue colour of the sky is due to the scattering of sunlight by the molecules of air.

Correct Answer is: (b) Poaceae

(b) Both (i) and (ii) are correct

1. Cereals belong to the family Poaceae.

2. Pulses belong to the family Fabaceae.

Binomial of lady’s finger is Abelmoschus esculentus. 

Family: Malvaceae.

• 1.Yes Production of two types of spores by a plant is called heterospory. Eg : Selaginella. 
• 2.Large spores are called megaspores and small spores are called microspores. Megaspore → Female gametophyte →Archegonia →egg. Microspore →Male gemetophyte →Antheridia →Antherozoids. 
•  3.The two gametophytes remain protected inside the respective spores in the sporophytic phase.
• Microspores are dispersed by wind and reach the Megaspore. The Antherozoid fuses with the egg toform zygote. 
• Thus the gametophytic generation is completed in the sporophyte plant itself. Only a er zygoteformation the female gametophyte is shed from the sporophyte. 
• This is a basic requisite for seed habit. 
• Distinguish apogamy and apospory. 
• 1.Apogamy - A type of reproduction occuring in some ferns in which the sporophyte develops from the gametophyte without fusion of gametes. 
• 2.Apospory - The development of a gametophyte directly from a sporophyte without the occurrence of mieosis or spore formation. 
• Both apogamy and apospory are seen in pteridophytes. 
• Why do mosses thrive only in moist habitat?
• Mosses (bryophytes) are non-vascular land plants of moist habitat that grow densely together ando en form green carpets or mats on damp soil. 
• It is because in the absence of roots, thallus absorbs water and minerals directly from ground oratmosphere. Hence, they can thrive only on moist places.

The answer is (d) Azolla

Coralloid roots of cycas have symbiotic association with Blue green algae. 

Which of the following is naked seed producing plant Gymnosperm. 

(c) Deuteromycetes 

 Yeast is a single celled fungus used in dairy industry.

(a) Cryptogams 

Amber is obtained from Gymnosperm. 

The stele is split into distinct collateral vascular bundles around the pith. Eg: Dicot stem.

• The term 'form genera' is used to name the fossil plants because the whole plant is not recovered as fossils instead organs or patts of the extinct plants are obtained in fragments.