Sodium chloride and calcium carbonate combine to form sodium carbonate and calcium chloride in the reversible reaction. 2NaCl + CaCO3 ⇌ Na2CO3 + CaCl2

Which statement about the reaction is necessarily correct?

1. The reaction will continue until the sodium chloride is used up.
2. The rate at which calcium chloride is equal to the rate at which sodium chloride is produced.
3. Both calcium carbonate and sodium carbonate are being produced.
4. The reaction is moving only from left to right.

Alead ball is dropped into a lake from a diving board 5m above the water . it hits the water with a certain velocity and then sink with constant velocity in bottom . it reaches the bottom 5 second after it is dropped if g= 10m/s2 . find depth of the lake and average velocity of the ball ?

If the new moon happens on january 15th, what shape will it be on february 6th?

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.