This is from dictionary: <span>a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
I would say it is 2</span>
Substances have different tendencies to donate or accept electrons. When a really good donor meets a great acceptor, the chemical reaction releases a lot of energy. Oxygen (O2) is the best electron acceptor and is used in many aerobic reactions (reactions with oxygen). Hydrogen gas (H2) is a good electron donor.
When O2 and H2 are combined, along with a catalyst, water (H2O) is formed. This example of a redox reaction can be written like this:

Chemical change, because the white powder heated the water and caused a thermal reaction, and possibly gas was produced due to bubbles.
Answer:
3.38 x 10⁴cm³
Explanation:
Given that:
Volume of the substance = 3.83 x 10⁷mm³
The problem entails use to convert from mm³ to cm³;
1000mm³ = 1cm³
So;
3.83 x 10⁷mm³ will produce 
= 3.38 x 10⁴cm³
Answer:
difference between metal and alloy is that the metal is a pure substance whereas the alloy is a mixture of two or more components.
Explanation:
Mostly the metalloids have the appearance just like the metallic appearance And also they are the brittle one's . Boron and silicon are the example. Note; By combining with other metals metalloid can form the alloy
