Which of the following is true about the elements on the Periodic Table? There may be 1 or more correct answers.

1. Block

2. True ( I'm unsure. He arranged it according to mass, but he is credited for the periodic table)

3. Noble gasses

4. technetium

5. Alkaline earth metals

6. Number of protons

7. False

8. Not true: generally decreases as atomic number increases within a period

9. Argon

10. Four

11. False

12. False

Explanation:

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

1.solid

2.carbon dioxide

3.helium