Work And Energy — Science STD 9 — Question

Which of the following in natural insecticides?

AIDS is due to:

1. Reduction to number of helper T-cells.
2. Reduction in number of killer T-cells.
3. Autoimmunity.
4. Non-production.

The energy possessed by wind is:

Archimedes' principle states that the buoyant force applied to an object 

Identify the type of force involved when loaded cart is moved:

Two elements X and Y have valencies of 5 and 3, and 3 and 2, respectively. The elements X and Y are most likely to be respectively:

1. Copper and sulphur.
2. Sulphur and iron.
3. Phosphorus and nitrogen.
4. Nitrogen and iron.

Which of the following contribute to green house effect?

1. Methane (CH₄).
2. Carbon dioxide (CO₂).
3. Chlorofluorocarbons (CFCs).
4. All of these.

The growing two or more crops at a time in a field is called as:

A freely falling object travels 4.9m in 1st second, 14.7m in 2nd second, 24.5m in 3rd second, and so on. This data shows that the motion of a freely falling object is a case of:

1. Uniform motion.
2. Uniform acceleration.
3. No acceleration.
4. Uniform velocity.