Answer:
Celsius is currently a derived unit for temperature in the SI system, kelvin being the base unit. ... The two main reference points of the Celsius scale were the freezing point of water (or melting point of ice) being defined as 0 °C and the boiling point of water being 100 °C.
Explanation:
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Answer: D) helium.
Explanation:
Nuclear fission is a process which involves the conversion of a heavier nuclei into two or more small and stable nuclei along with the release of energy.

Nuclear fusion is a process which involves the conversion of two small nuclei to form a heavy nuclei along with release of energy.
Example: 
Thus when deuterium and tritium , the two isotopes of hydrogen are fused, a heavier nuclei helium is being formed from two smaller nuclei releasing a neutron.
Answer: Ca(OH)2 (aq) + H2SO4 (aq) ----------> CaSO4(aq) + 2H2O(l)
Explanation:
Since this is a neutralization reaction, the end product would be salt and water. In this equation Calcium will displace hydrogen from the acid because it is more reactive, resulting in the formation of CaSO4 (salt), while the displaced H2 molecule combines with OH molecules to form water.
The equation of the reaction is thus;
Ca(OH)2 (aq) + H2SO4 (aq) ----------> CaSO4(aq) + H2O(l), in other to balance it, we add ''2'' to the water molecule in the right hand side of the equation.
Balance equation is
Ca(OH)2 (aq) + H2SO4 (aq) ----------> CaSO4(aq) + 2H2O(l)
Answer:
2Na⁺ (aq) and 2OH⁻(aq)
Explanation:
Spectator ions:
Spectator ions are those ions which are same on both side of chemical reaction. These ions are same in the reactant side and product side. Their presence can not effect the chemical equilibrium that's why when we write the net ionic equation these ions are neglect or omitted.
Given ionic equation:
Ba⁺²(aq) + 2OH⁻(aq) + 2Na⁺ (aq) + CO²⁻₃(aq) → BaCO₃(s) + + 2Na⁺ (aq) + 2OH⁻(aq)
In given ionic equation by omitting the spectator ions i.e, 2Na⁺ (aq) and 2OH⁻(aq) net ionic equation can be written as,
Net ionic equation:
Ba⁺²(aq) + CO²⁻₃(aq) → BaCO₃(s)
Answer:
Melting is the process of being changed from a solid to a liquid state especially by the application of heat. This occurs when the energy of the solid increases, which increases the substance's temperature to the melting point. Typically, the solids energy increases by the application of heat or pressure. At the melting point, the ordering of molecules in the solid breaks down to a less ordered state, and the solid "melts" to become a liquid.
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