What is the earth land masses made out of

After fidel castro became the leader of cuba, many cubans moved to the united states. why did cubans leave their home country? a. job opportunities b. religious reasons c. political reasons d. educational opportunities

Read the paragraph and answer the question that follows: the town of belmond, iowa, needs to add weather sirens. the loud and steady wail would warn citizens of approaching danger. if past history is an indication, the sirens will save hundreds of lives. with a prediction of a deadly storm season, the alert which sentence should be revised to eliminate redundancy? the town of belmond, iowa, needs to add weather sirens. the loud and steady wail would warn citizens of approaching danger. if past history is an indication, the sirens will save hundreds of lives. with a prediction of a deadly storm season, the alert system is needed immediately.

The pka of three different c―h bonds is given below. explain the observed trend in pka. select the single best answer.