Answer:
Q2->They all form acids when combined with hydrogen. They are all fairly toxic. They readily combine with metals to form salts.
Q3->Because their outermost orbit is complete. In Mendeleev's original periodic table there was no place reserved for noble gas. They were discovered in end of 19th century. So Mendeleev created zero group without disturbing original periodic table.
Explanation:
C, The ground movements (vibrations) caused by seismic waves. Example: Earthquakes. Hope this helped!
Evolution is how we came to be as human beings ranging from rats, apes etc. This has helped us increase our survival skills and communication (ever since the beginning)
Answer:
The correct answer is: B. The amount of air in a room never changes.
Explanation:
- A system is said to be in equilibrium when the net components in the system remains constant (no increase or decrease) with time.
- The air in a room never remains constant and always undergoes dynamic movement into and out of the room. At equilibrium, the net air in the room remains constant as amount of air exiting the room is balanced by the amount of air entering it.
- Evaporation of water in the form of water vapour from a cup into the atmosphere is not in a state of equilibrium as the amount of water evaporating from the cup is not replaced in the cup so there is a net decrease in water level in the cup.
- The decrease in nitrogen percentage in a room is not in equilibrium as the nitrogen concentration of the room is not constant.
- A blade of grass growing taller is not in equilibrium as a constant height of the grasses is not maintained.
