Which of the following is always altered when a substance undergoes a chemical change?
a- state of matter of the substance
b- color of the substance
c- mass of the substance
d- arrangement of the atoms composing the substance

The air is going to come out because of the low pressure.

Answer(2) electrons;

The question is incomplete. complete question is attached belowanswer: correct answer is option b  i.e.  solid particles  reason: filter paper has small pores, through which smaller particles can pass through. however, solid particles  have relatively larger size. hence, they are least likely to pass through.

Aquantity of that isotope to decay to 1/2 of  its original value