How many moles are present in 11.6 g of Butane?

$$\text{Number of moles} = 0.2 \text{ mol}$$

The number of moles present in 11.6 g of butane is:

$$\boxed{0.2 \text{ mol}}$$

Now, let's address the questions from Figure 7.

Question 7(i): Copy the figure and indicate the following: -The direction of current, -The polarity and -The magnetic field lines

• The current flows from the positive terminal (the longer line of the DC source on the left) through the switch and rheostat. It enters the solenoid from the right end, flows over the top of the coil, and exits from the left end, returning to the negative terminal of the DC source.
• Using the Right-Hand Grip Rule (curling fingers in the direction of current over the coil), the thumb points to the left. Therefore, the left end of the solenoid is the North pole, and the right end is the South pole.
• Magnetic field lines emerge from the North pole (left end) and enter the South pole (right end) outside the solenoid. Inside the solenoid, the field lines run from the South pole (right end) to the North pole (left end), forming continuous closed loops.

Question 7(ii): State one method of making the field stronger.

• One method to make the magnetic field stronger is to increase the current flowing through the solenoid.

Question 7(iii): Name one device which makes use of electromagnetism.

• An electric bell is a device that makes use of electromagnetism.