The answer is HB!
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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:

Covalent compounds are composed of atoms that are linked via covalent bonds i.e. bonds formed by mutual sharing of electrons. This is in complete contrast to ionic compounds which are held together by ionic bonds, i.e. bonds formed by complete transfer of electrons from one atom to the other.
In the given examples we have:
Barium nitrate: Ba(NO3)2 - Ionic
Dinitrogen tetroxide: N2O4- Covalent
Boron trifluoride: BF3-Covalent
Ammonium sulfate: (NH4)2SO4- Ionic
Carbon tetrachloride: CCl4- Covalent
Barium chloride: BaCl2 - Ionic
Answer:
When we increase the temperature of one of the reactants in a chemical reaction, this increases the particles kinetic energy, making them move much faster than they were before. This also increases the chance of a more successful collision and the rate of reaction.
Explanation:
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In a solid, molecules are packed together, and it keeps its shape. Liquids take the shape of the container. Gases spread out to fill the container. Solid is one of the three main states of matter, along with liquid and gas.
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