Available Answers

1. 1.

   Fill in the blanks.

   1. A weighing balance is a ______________________ with the fulcrum at the centre.
   2. The coil of wire inside a bulb is called the ___________________.
   3. When the filament of a bulb melts, the bulb _____________________.
   4. Rockets use _____________________ propulsion to fly.
   5. The coil of wire inside a heating device is called a heating _____________________.
2. 2.

   Write 'True' or 'False'.

   1. Standard weights have fixed weights.
   2. Heat is produced when electricity passes through something.
   3. The filament of a bulb is made of a nonmetal.
   4. The heat produced when electricity passes through something depends on the material the thing is made of.
   5. Jets carry their own supply of oxygen.
   6. Some aquatic animals use jet propulsion.
3. 3.

   Dishonest shopkeepers fool customers while weighing things with a weighing balance. Think of one way in which shopkeepers do this.
4. 4.

   Rockets carry liquid oxygen. Why do they not carry oxygen in the gaseous form?
5. 5.

   Some aquatic animals use jet propulsion to move through water. Do you think a boat can be designed to make use of jet propulsion?