Answer:
the study of the structure, reaction, and composition of different kinds of substances
Explanation:

Answer: Before about week 8 of pregnancy, a doctor may refer to the fetus as an embryo. The heart of an embryo starts to beat from around 5–6 weeks of pregnancy. Also, it may be possible to see the first visible sign of the embryo, known as the fetal pole, at this stage.
Answer:
1. False 2. True 3. False 4. True
Explanation: