The altitude of polaris measured by an observer at the tropic of cancer is 1) 15° 2) 23.5° 3) 66.5° 4) 90°

Explanation:

The Tropic of Cancer is one of the parallels (imaginary line around the Earth parallel to the equator) located in the northern hemisphere (currently its latitude is ).

It is called "Cancer" because a long time ago, when the summer solstice occurred in the northern hemisphere (on June 20th or 21st), the Sun was in the constellation Cancer (the crab).

Now, if we were just in the North Pole, Polaris would by exactly over our heads ( over the horizon), but as we go south and find the Tropic of Cancer parallel, Polaris altitude will be approximately at an angle of over the horizon.

Hence, the altitude of Polaris measured by an observer at the Tropic of Cancer is .

answer; (d) melting of sea ice;

because the two particles have an equal charge, the charges will cancel out and give the atom an overall charge of 0. so, if at atom has 35 protons in the nucleus, we could expect it to have 35 electrons orbiting that nucleus.