Will it be too heavy for girls to thin their arms with 2 kg dumbbells, and will they grow muscles?
No, as long as you practice a certain amount. You won't gain muscle, just don't exercise too much, usually between 0.5 and 2.5 kilograms. Of course, this is a rough figure, which is suitable for the public. At best, it is measured by your figure. Ask more classmates and coaches, and then sum up the slimming plan based on your own experience. Remember, planning is a general trend, which can change with the increase of experience.