In an undisturbed sequence of layers of rocks, the younger layers lie on top of the older layers
Answer:
- <em>To balance a chemical equation it may be necessary to adjust the </em><u>coefficients.</u>
Explanation:
The <em>coefficients</em> of a <em>chemical equation</em> are the numbers that you put in front of each reactant and product. They are used to balance the equation and comply with the law of mass conservation.
By adjusting the coefficients you obtain the relative amounts (moles) of each product and reactant, i.e. the mole ratios.
Here an example.
The first information is what is called a word equation. E.g. nitrogen and hydrogen react to form ammonia:
- Word equation: hydrogen + nitrogen → ammonia
- Skeleton equation: H₂ + N₂ → NH₃
This equation shows the chemical formulae but it is not balanced. The law of mass conservation is not observed.
So, in order to comply with the law of mass conservation you adjust the coefficients as follow.
- Balanced chemical equation: 3H₂ + N₂ → 2NH₃
As you see, it was necessary to modify the coefficients. Now the law of conservation of mass is observed and you get the mole ratios:
- 3 mol H₂ : 1 mol N₂ : 2 mol NH₃
Answer: potassium iodide is the basic test for starch,and the positive test is blue-black coloration, any other test substance which is not starch will give a negative results.
Explanation:
Starch is an example of polysaccharide and since the standard test for it is potassium iodide solution, it gives a positive test.
Diasaccharides e.g maltose are reducing sugars.their standard test is BENEDICT test .
Therefore, in the hydrolysis; starch should give a positve test, while Diasaccharides should give negative rest.
