C is the first & the second question is A
Answer:
1/8 = (1/2)^3
This implies the sample has decayed for 3 half lives
3 * 5730 yrs = 17,200 years
Wrap around a metal with wire instead of using wire alone.
One way of removing nitrogen gas from the atmosphere is by natural nitrogen fixation. This is done by nitrogen-fixing bacteria in the oceans and in the soil. Nitrogen fixation is a process that converts the nitrogen in air to ammonia.
Answer: b) they are the areas where Earth's magnetic field is weakest
Explanation:
According to classical physics, a magnetic field always has two associated magnetic poles (north and south), the same happens with magnets. This is because for <em>classical physics</em>, naturally, magnetic monopoles can not exist.
In this context, Earth is similar to a magnetic bar with a north pole and a south pole. This means, the axis that crosses the Earth from pole to pole is like a big magnet.
Now, by convention, on all magnets the north pole is where the magnetic lines of force leave the magnet and the south pole is where the magnetic lines of force enter the magnet. Then, for the case of the Earth, the north pole of the magnet is located towards the geographic south pole and the south pole of the magnet is near the geographic north pole.
Being the magnetic poles the places where the Earth's magnetic field is weakest. And it is for this reason, moreover, that the magnetic field lines enter the Earth through its magnetic south pole (which is the geographic north pole).
