Which is the correct chemical equation for the following statement? “Sodium reacts with oxygen in a 2 to 1 ratio to produce sodium oxide.” Na 2 + O 2 ® 2 N aO
Na 2 O + O 2 ® 2 N a
Na 2 O ® 2 N a + O \2
4Na + 2O 2 ® 2Na 2 O

Phase changes are chemical changes. true or false

When you jump from an elevated position you usually bend your knees upon reaching the ground. by doing this, you make the time of the impact about 10 times as great as for a stiff-legged landing. in this way the average force your body experiences is a) less than 1/10 as great. b) more than 1/10 as great. c) about 1/10 as great.d) about 10 times as great.

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.