Which of the following statements are true?
check all that apply.
o a positive charge and a negative charge attract each other.
o electric charge is conserved.
o two positive charges attract each other.
o a neutral object contains no charge.
o two negative charges repel each other.
o electric charge is quantized.

The following statements are true:

1) A positive charge and a negative charge attract each other.

2) Electric charge is conserved.

3) A neutral object contains no charge.

4) Two negative charges repel each other.

5) Electric charge is quantized.

Explanation:

1) Experimentally, it has been showed that there are two types of charges (arbitrarily defined as positiva and negative), and that there exists a force between them, being attractive between opposite types of charges.  

2) The charge is a fundamental property of matter, and like energy, must be always conserved. It can't neither be created nor destroyed.

3) A neutral object contains no net charge, being equal the number of positive and negative charges in it, so they counteract each other, being the net effect null, so it is said that the object is neutral.

4) As stated in (1) , there exists two types of charges, and it had been experimentally found that charges of the same type repel each other, so two negative charges repel each other.

5) Any charge is ultimately a set of electrons and/or protons, so it is always a multiple of the elementary charge carried by one of them, equal to 1.6*10⁻¹⁹ coulombs (unit of electric charge), so we can conclude that the charge is quantized.

vapour or gas assuming atmospheriv pressure