Answer: To show the number of atoms present.
Explanation: As in CO² (Carbon dioxide), there is a small 2 next to the symbol "O" (oxygen) to explain that there are two oxygen atoms.
Answer:
Waves carry energy from place to place.
Explanation:
Some waves are used for mainly communication and phone signals. They help people get internet in the middle of nowhere if you are near an energy wave.
Answer: A) grinding coffee beans
Explanation:
A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.
A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.
1. Grinding coffee : Only change in size takes place, thus a physical change
2. Baking a cake: the chemical reaction occurs by combination of flour with oxygen , thus a chemical change.
3.:converting water to hydrogen and oxygen: The decomposition iof water takes place, thus is a chemical change
4.Burning of coal: the chemical reaction occurs by combination of carbon with oxygen , thus a chemical change.
Answer:
83.69 gm
Explanation:
molar weight of N2 = 28
Find the number of moles then multiply by this
1.8 x10^24/ (6.022x10^23) * 28 =83.69 gm
Answer:
I think It's C
Explanation:
due to higher waves can get easy transfers and receive those signals for most things, such as radios, TVs, phone signals etc etc
