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.
<h2>Gelatin </h2>
Explanation:
Gelatin is a differential medium which tests the ability of an organism to produce an exoenzyme, called gelatinase (this enzyme hydrolyzes gelatin)
When gelatin is at a temperature below 32°C (or within a few degrees thereof), it is a semisolid material and at temperatures above 32°C, it is a viscous liquid
When gelatin is broken down, it can no longer solidify and if an organism can break down gelatin, the areas where the organism has grown will remain liquid even if the gelatin is refrigerated
No the conclusion by student is not right because the tube must be runny after incubation followed by refrigeration to be considered gelatinase positive
Kingdom because there are 3 kingdoms - Eukarea, Prokarya and Archaea
