Answer: The ion that contribute to water hardness are:
--> a. Ca2+
--> b. (HCO)3^- and
--> c. Mg2+
While K+ DOES NOT contribute to water hardness.
Explanation:
WATER in chemistry is known as a universal solvent. This is so because it is polar in nature and dissolves most inorganic solutes and some polar organic solutes to form aqueous solutions. It is composed of elements such as hydrogen and oxygen in the combined ratio of 2:1.
Water is said to be HARD if it does not lather readily with soap. There are two types of water hardness:
--> Permanent hardness: This is mainly due to the presence of CALCIUM and MAGNESIUM ions in the form of soluble tetraoxosulphate(VI) and chlorides. These ions are removed by adding washing soda or caustic soda.
--> Temporary hardness: This is due to the presence of calcium HYDROGENTRIOXOCARBONATES. It can be removed by boiling and using slaked lime.
Therefore from the above given ions, Ca2+,(HCO)3^- and Mg2+ contributes to water hardness.
Answer:
1. True
2. False
3. False
4. True
Explanation:
A lab is an abbreviation for laboratory and it can be defined as a building that is equipped with scientific equipments and apparatus, which are used for performing scientific experiments, manufacturing of chemicals and drugs, research, testing and analysis of hypothesis in order to establish a theory.
Generally, laboratory scientists, technicians, students and anyone going into a laboratory is prohibited from taking in edible items such as food and water.
Basically, all laboratories are required to place a visible warning sign around the lab prohibiting the bringing in and ingestion of food in any form.
1. True: Tobacco products of all kinds are prohibited in lab.
2. False: Beverages are allowed in lab as long as they are in containers with lids. It's completely prohibited from the lab so as to prevent food poisoning.
3. False: Chewing gum is okay in the lab as long as you don't blow bubbles.
4. True: Food items should not be brought into the lab.
Answer: Option (c) is the correct answer.
Explanation:
Photosynthesis is a process in which sunlight, carbon dioxide, and water is used by the plants to make their on food.
Plants absorb energy in the form of heat from the sunlight and thus produce glucose and oxygen from carbon dioxide and water. This absorbed energy is then used to start various chemical and biochemical reactions in the plants.
Hence, photosynthesis is an endothermic reaction.
Thus, we can conclude that a large amount of energy is required to activate the reaction.
