Rainbow

Q.

A squirrel is in a scary situation. Its body has to prepare for either fighting or running away. State the immediate changes that take place in its body so that the squirrel is able to either fight or run?

Q.

A piece of iron weighs $155gf$ in air and $133gf$ in water. What is its volume and the relative density of the iron? What would be the same piece of iron appear to weigh in alcohol of density $0.8g/c{m}^3$?

Q.

What is the relationship between the buoyant force and the weight of liquid displaced?

Q. The mass of a body is the total amount of matter present in it, and is measured in $\text{kg}$.

1. True
2. False

Q.

Identify the most reactive and least reactive metal from the following-

$Hg,Na,Fe,Ag$

Q.

Question 11
The bluish colour of water in deep sea is due to

(a) the presence of algae and other plants found in water
(b) reflection of sky in water
(c) scattering of light
(d) absorption of light by the sea

Q. The condition(s) for total internal reflection is/are:

1. Light must travel from denser to rarer medium.
2. The angle of incidence should be greater than the critical angle.
3. The angle of incidence should be greater than the angle of refraction.
4. The angle of incidence should be greater than the angle of reflection.

Q.

The mass of an object is $20g$ and its volume is $4c{m}^3$ . What is its density?

Q. We see the rainbow on the side of the sun.

1. opposite
2. same
3. left
4. right

Q.

The substance having the highest density is :

1. Gold

2. Alluminium

3. Osmium

4. Zinc

Q. What is the valency of the group 2 and group 15 elements, respectively?

1. 2, 2
2. 2, 3
3. 2, 1
4. 2, 4

Q.

Define Reactivity Series.

Q.

A piece of wood has dimensions $1m\times 2m\times 3m$ and a mass of $2kg$. What is the density of wood and will the piece float in water?

$[{\rho }_{water}$ = 1000 $kg{m}^{-3}]$

1. $0.33kg{m}^{-3}$, Yes

2. $0.33\times {10}^{-3}kg{m}^{-3}$, No

3. $3kg{m}^{-3}$, Yes

4. $3\times {10}^{-3}kg{m}^{-3}$, No

Q. The gravitational pull of the Earth acting on a body is known as the body's weight.

1. True
2. False

Q.

Buoyant force equals to the weight of displaced liquid.

1. True
2. False

Q.

A ballon filled with hydrogen gas rises upwards because

1. hydrogen is an element

2. hydrogen is colourless gas

3. the weight of ballon is less than the weight of air displaced by it

4. the weight of ballon is more than the weight of air displaced by it

Q. If a bag of rice weighs $30\text{kg}$ on Earth, what is the weight of the rice bag on the planet Neptune? Take the mass of Neptune to be ${10}^{26}\text{kg}$, and its radius to be $25\times {10}^6\text{m}$.

1. $110\text{N}$
2. $320\text{N}$
3. $150\text{N}$
4. $60\text{N}$

Q. The inferences supporting the Big Bang Theory are:

1. All galaxies are drifting away from one another.
2. The separation of galaxies is due to an explosion.
3. Stars and asteroids are coming closer in an exponential rate.
4. Planets are shrinking exponentially.

Q.

An empty density bottle weights$22g.$ When filled completely with water, its weights $\mathbf{50}\mathbf{}\mathit{g}$and when completely filled with brine solution it weighs $54g$.

Calculate

(a) Volume of density bottle

(b) the density of brine solution.

Q.

Name the liquids shown in the diagram given below.

Q. Calculate the buoyant force (in $N$) acting on a $250\text{g}$ rubik's cube of side length $8\text{cm}$, if only half of it is submerged in kerosene. The rubik's cube is hanging by a thread. Density of kerosene is $0.8\text{g}{\text{cm}}^{-3}$. Take $\text{g}=10\text{m}{s}^{-2}$.

1. 2.048

Q. The deeper a body is in a liquid, the lesser the pressure acting on it.

1. True
2. False

Q.

What is the activity (or reactivity) series of metals?

Q. Statement I: Lithium needs less energy to have an electron knocked off from its outermost orbit than does helium.

Statement II: Lithium has one electron in its outermost orbit which is loosely bound due to the repulsion of the inner orbit electrons.

1. Statement I is true. Statement II is true. Statement II is the correct explanation of statement I.
2. Statement I is true. Statement II is true. Statement II is not the correct explanation of statement I.
3. Statement I is true. Statement II is false.
4. Statement I is false. Statement II is false.

Q.

A sealed cane weighing 600 g has a volume of $400c{m}^3$. Will this cane sink in the water? The density of water is $1g/c{m}^3$.