Q. Water at normal atmospheric pressure boils at :

1. $250K$
2. ${100}^{\circ }C$
3. $0^{\circ }C$
4. ${50}^{\circ }C$

Q. Name the simplest hydrocarbon.

Q. Write the Lens maker's formula and explain the terms in it.

Q. The mirror used by E.N.T. specialists is _____

1. Convex
2. Concave
3. Plane
4. None of these

Q. The size of an object as perceived by an eye depends primarily on _____ .

1. Actual size of the object
2. Distance of the object from the eye
3. Size of the image formed on the retina
4. Aperture of the pupil

Q. The current in the wire depends _____

1. Only on the potential difference applied
2. Only on the resistance of the wire
3. On potential difference and resistance
4. None of them

Q. Write the balanced chemical reaction for the following and identify the type of reaction in each case.
(A) $Magnesiu{m}_{\left(a\right)}+Iodin{e}_{\left(g\right)}\to Magnesiumiodid{e}_{\left(s\right)}$
(B) $Zin{c}_{\left(s\right)}+Hydrochloricaci{d}_{\left(aq\right)}\to Zincchlorid{e}_{\left(aq\right)}+Hydroge{n}_{\left(g\right)}$

Q. State any two differences between Convex and Concave mirrors.

Q. Rainbow is an example for continuous spectrum. Explain.

Q. Explain, why dogs pant during hot summer days using the concept of evaporation?

Q. Draw a neat diagram of an A.C. generator.

Q. Which of the following is Snell's law?

1. $\frac{n_1}{n_2}=\frac{\sin r}{\sin i}$
2. $\frac{n_2}{n_1}=\frac{\sin r}{\sin i}$
3. $n_1\sin i=\frac{\sin r}{n_2}$
4. $n_2\sin i=constant$

Q. A house has four tubelights, three fans and a television. Each tubelight draws $40W$. The fan draws $80W$ and the television draws $100W$. On an average, all the tubelights are kept on for $5$ hours, all fans for $12$ hours and the television for $6$ hours everyday. Find the cost of electric energy used in $30$ days at the rate of $Rs.3.00$ per KWH

Q. What is meant by water of crystallization of a substance? Describe an activity to show the water of crystallization.

Q. If an object is placed at ${}^{\prime }{C}^{\prime }$ on the principal axis in front of a Concave mirror, the position of the image is ______

1. At infinity
2. Between $F$ and $C$
3. At $C$
4. Beyond $C$

Q. What is the reason for using Tungsten as a filament in electric bulb?

Q. By observing steel vessels and different images in them, Ramu, a third class student asked some questions to his elder sister Santha. What may be those questions?

Q. Write any two uses and two properties of covalent compounds.

Q. Write about your favourite scientist/physicist.

Q. Which converts Electrical energy into Mechanical energy?

1. Motor
2. Battery
3. Switch
4. Generator

Q. Three bodies $A,B$ and $C$ are in thermal equilibrium.
The temperature of $B$ is ${45}^{\circ }C$. Then the temperature of ${}^{\prime }{C}^{\prime }$ is _____

1. ${45}^{\circ }C$
2. ${40}^{\circ }C$
3. Any temperature
4. ${50}^{\circ }C$

Q. What is Humidity?

Q. Define critical angle.

Q. Which method do you suggest for extraction of high reactivity metals? Why?

Q. What do you mean by electric shock? Explain how it takes place?

Q. How can you verify that a current carrying wire produces a magnetic field with the help of an experiment?

Q. What is a Chemical bond?

Q. Where do we use washing method in our daily life? Give examples. How do you correlate this example with enrichment of ore?

Q. Draw a neat diagram of Reverberatory furnace and label its parts?

Q. Mention two methods, which produce very pure metals.