Need help with these questions in my engineering class

Complete the statement about memory improvement. ( )involves organizing and breaking down information into easier groups to expand capacity. rehearsal is the verbal repetition of information. these techniques are especially important for the improvement of ( ) memory.

Determine the force the sun exerts on an object with a mass of 80.0 kg if that object is on the earth. what is the force exerted by the moon on the same object? what is the force the earth exerts on it?

Which of the following is not a double-replacement? a.) hno3 (aq) + kho (aq) -> h2o (l) + kno3 (aq)b.) ba(oh)2 (aq) + 2hclo4 (aq) -> ba(clo4)2 (aq) + 2h2o (l)c.) naoh (aq) + hcl (aq) -> h2o (aq) + nacl (s)d.) zn (s) + 2hcl (aq) -> h2 (g) + zncl2 (s)