Answer:
The correct answer is A. 3O₂ + 2Al → 2AlO₃
Law of conservation of mass states that mass can nether be created nor destroyed in a closed system or chemical reaction i.e. the total mass of the matter always remains the same throughout the chemical or physical change.
For example, in the given reaction 3O₂ + 2Al → 2AlO₃ the total mass of the reactants is equal to the total mass of the product.
Mass of oxygen = 16 x 3 = 48 AMU
Mass of aluminium = 2 x 27 = 54 AMU
Total molecular mass of the reactants = 102 AMU
Total molecular mass of the product = 2 x 27 + 6 x 8 = 102 AMU.
Hence, the total mass of the matter remains the same.
Answer:
D. Psychrophile
Explanation:
Psychrophiles or cryophiles are a type of extremophiles i.e. they live in extreme environment. They grow well in low temperatures ranging from -20 to +10 degree Celsius.
Here, the bacteria was incubated at different temperatures. It did not show growth at standard incubation temperature of 37°C which indicates that it might be an extremophile preferring either very hot or very cold environment. But it also did not show growth at 50°C which means that it does not survive well at high temperature.
Lab bench top has generally colder surface compared to the surrounding environment and a little growth was observed there which indicates that this bacteria might require cold temperature for growth. The result was finally confirmed with abundant growth observed inside refrigerator which is only possible if it is a psychrophile.
