If element X has 21 protons, How many electrons does it have?

Name the two sources of heat on Earth.

1. Is the sequence geometric? If so, identify the common ratio. 6, 12, 24, 48, ... yes; 2 yes, - 2 yes; 4 no 2. What is the fifth term of the geometric sequence? 5, 15, 45, ... 1,215 1,875 405 3,645

Name and classify Si and Sb. A) Sarium and siobium are metals. B) Silicon and antimony are metalloids. C) Silinium and sirbonium are non-metals. D) Silver and seaborgium are transition metals.

A rock has mass 1.80 kg. When the rock is suspended from the lower end of a string and totally immersed in water, the tension in the string is 12.8 N. What is the smallest density of a liquid in which the rock will float?

a neutral atom prossesses an atomic number of 15 and an atomic mass of 31. thress electrons are gained. what is the result of this conversation

A student is trying to calculate the density of a ball. She already knows the mass, but she needs to determine the volume as well. Which of the following formulas can be used to calculate the volume of the ball?

Is there such a thing as real time weather radar? why not?

Luke and Carrie are driving down a straight section of the interstate at 70 mph in Luke's new convertible. Carrie is drinking a soda in the passenger seat.

A force produces power p by doing work w in a time t. what power will be produced by a force that does six times as much work in half as much time?

A batter hits a baseball with a bat. The bat exerts a force on the ball. Does the ball exert a force on the bat?