Astudent walks 2 km in 30 minutes. what is the student’s average speed in km/h?

Which statement justifies that phosphine (ph3) is a polar molecule?

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17

Scientists often have to deal with numbers that are either very large or very small. for example, the radius of the sun is approximately 696,000 kilometers, while bacterial cells are as small as 1.9 × 10-4 millimeters. express each number in an alternate form.