if an atom has 4 protons, 5 neutrons, and 4 electrons, what is the mass number of this atom? How do you know?

Why must water be heated at about 80 degrees during esterification

Which would best be explained using Newton's third law? A) a gun moves backward while firing a bullet. B) a bicyclist coasts down from the top of a hill C) a car stops short and passengers moves forward.

The total pressure of a mixture of co2 and o2 is 780 mmhg. if the pressure of the co2 is 560. torr, what is the pressure of o2?

Calculate the amount of sulfuric acid h2so4, which contains 6.02 x 1023 atoms of oxygen.

What is the mass of mole of calcium carbonate

Which of the following atoms has seven valence electrons? chlorine (Cl) nitrogen (N) manganese (Mn) oxygen (O)

A.) During an experiment, a student adds 2.90 g of CaO to 400.0 mL of 1.500 M HCl. The student observes a temperature increase of 6.00 °C. Assuming the solution/'s final volume is 400.0 mL, the density if 1.00 g/mL, and the heat capacity is 4.

Consider the ionic compound magnesium acetate. How many electrons does the magnesium ion have

What are two parts of the peripheral nervous system

Why is it problematic for some of a prescription cream to get on the outside of the jar?