Calculate the mass of nacl needed to make 40% solution from 3kg of water ? could you explain step by step : -)

After cloud droplets form, what must happen to them for precipitation to occur?

What is the most stable monatomic ion formed from nitrogen

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space