Answer:
They give off their own light energy
Explanation:
I'm taking astronomy and I answered this questions not too long ago
Answer:
group 1 and are called Alkali metals. Similarly, very active non-metals are placed in group 17
Explanation:
Answer:
Explanation:
In weight/volume (w/v) terms,
1 ppm = 1g m-3 = 1 mg L-1 = 1 μg mL-1
200 mL = 0.2 L
15 / 0.2 mg L-1 =75 ppm