Acids, Bases and Salts — Science STD 10 — Question

Name the five types of tropisms. How are tropic movements helpful to plants? Explain with an example.

Consider the following elements:
Na, Ca, Al, K, Mg, Li.

1. Which of these elements belong to the same period of the periodic table?
2. Which of these elements belong to the same group of the periodic table?

Which of the two is a cleaner fuel: hydrogen or CNG? Why?

The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. If speed of light in glass is 2×108 m/s, find the speed of light in water.

A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that he moves gradually the flame towards the lens and each time focuses its image on the screen.

1. In which direction does he move the lens to focus the flame on the screen?
2. What happens to the size of the image of the flame formed on the screen?
3. What difference is seen in the intensity (brightness) of the image of the flame on the screen?
4. What is seen on the screen when the flame is very close (at about 5 cm) to the lens?

The construction of large dams leads to social and environmental problems. List two problems of each category.

Draw a ray diagram to show the path of the reflected ray corresponding to an incident ray of light parallel to the principal axis of a convex mirror and show the angle of incidence and angle of reflection on it.

What measures would you take to conserve electricity in your house?

State the rule to determine the direction of a:
Force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it.

What is photosynthesis?