Isotopes are chemical elements with same atomic number (Z), but different mass number (different number of neutrons).
Hydrogen is an element with atomic number 1. It has three isotopes:
1) protium (₁¹H), with mass number 1 (no neutrons).
2) deuterium (₁²H), with mass number 2 (one neutrons, n° = 2 -1, n° = 1).
3) tritium (₁³H), with mass number 3 (two neutrons, n° = 3 -1, n° = 2).
C. Walking on wet floors shows that Friction is undesirable
Answer:
Energy in foods is provided by macro-nutrients.
Explanation:
Nutrients are “environmental substances” used for growth, energy, and bodily functions of the organisms. Those nutrients that are required in larger amounts are called macro-nutrients.
There are 3 macro-nutrients needed by humans: lipids (fats), carbohydrates (sugar) and proteins. All these macro-nutrients gives energy in form of “calories”. For example:
- In carbohydrates, there are '4 calories' of energy per gram.
- In proteins, there are '4 calories' of energy per gram.
- And in lipids, there are '9 calories' of energy in one gram.
This means that if you look at a food label and it lists 10 grams of carbohydrates, 0 grams of protein, and 0 grams of fat, that food would contain 40 calories.
Answer : The correct option is A.
Explanation :
The given chemical reaction is,
In the reaction, Reactants are present on the left side of the arrow and products are present on the right side of the arrow.
Reactants are those which takes part in and undergoes change during the reaction.
Products are those which are formed during the reaction.
In the given reaction, zinc react with hydrochloric acid to form zinc chloride and hydrogen gas.
Therefore, the reactants are zinc and hydrochloric acid.
