F 500 Joules of work are required to move a Cinder block 35 meters, what is the mass of the block?

Can someone me with questions 12 and 13 plz.

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?

Pl what kind of reaction is this? nahco3 + h2o → co2 + naoh + h2o -composition -decomposition -single replacement -double replacement im leaning more toward single replacement. if im wrong can you explain whyy?