Water and dimond are the 2 pure substances
Answer:
Option D. 30 g
Explanation:
The balanced equation for the reaction is given below:
2Na + S —> Na₂S
Next, we shall determine the masses of Na and S that reacted from the balanced equation. This is can be obtained as:
Molar mass of Na = 23 g/mol
Mass of Na from the balanced equation = 2 × 23 = 46 g
Molar mass of S = 32 g/mol
Mass of S from the balanced equation = 1 × 32 = 32 g
SUMMARY:
From the balanced equation above,
46 g of Na reacted with 32 g of S.
Finally, we shall determine the mass sulphur, S needed to react with 43 g of sodium, Na. This can be obtained as follow:
From the balanced equation above,
46 g of Na reacted with 32 g of S.
Therefore, 43 g of Na will react with = (43 × 32)/46 = 30 g of S.
Thus, 30 g of S is needed for the reaction.
Answer:
A pure solid is heated and turns into a pure liquid.
Explanation:
No colour change recorded, only change of state, hence this is a physical change - physical changes I.e. change of state and temperature are not chemical reactions.
Answer:
1. There are so many ethical concerns about biotechnology, some Ethical issues that arise from the application of modern biotechnologies include:
Discrimination of individuals because of their health or health history as a result of knowing their genetic information, minimizing harms while maximizing benefits, Interference with nature, privacy.
2. a. Plants (maize, rice)
b. Fish (GloFish)
3. For individuals, biotechnology has helped in the prevention and treatment of a wide range of diseases. For society, biotechnology saves time, improves the health and quality of food through a reduction in the use of pesticides and it can create new viruses and bacteria that cause diseases. Biotechnology could address global change since more genetically modified plants are grown.
