Pleeaasee hellpp me ??

If element x has 99 protons how many electrons does it have

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.

The brightest star in the night sky in the northern hemisphere is sirius. its distance from earth is estimated to be 8.7 light years. a light year is the distance light travels in one year. light travels at a speed of 3.00 × 108 m/s. calculate the distance from earth to sirius in miles. (1 mi = 5280 ft) g