Answer: It was known as the SPACE RACE.
Explanation: The space race was a cold war between the Soviet Union (USSR) and the United States (US), to get satellites and humans into space. The competition began in earnest on August 2, 1955, when the Soviet Union responded to the US announcement. On April 12, 1961, the USSR surprised the world again by launching Yuri Gagarin into a single orbit around the Earth in a craft they called Vostok 1.
Answer : The standard enthalpy of formation of ethylene is, 52.4 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation reaction of 
will be,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
(3) 
Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equation, we get :
(1) 
(2) 
(3) 
The expression for enthalpy of formation of will be,
Therefore, the standard enthalpy of formation of ethylene is, 52.4 kJ
<span>Electronegativity is the property of an element that measures the
ability of it to attract and form electron bonds. The trend in the periodic
table in terms of electronegativity decreases from right to left and from top
to bottom. In the case of period 4, the element with the highest electronegativity
is bromine. </span>
Explanation:
Both conduction and convection are both forms of heat transfer from one place to another.
- In conduction, there must be contact between two bodies for the process to take place but in convection, the matter moves to transfer heat.
- Conduction mostly occurs in solid substances whereas convection occurs mostly in fluids.
- Heat transfer in conduction is quite slow compared to convection which is much faster.
Example of conduction is heating of iron pot when cooking
Example of convection is the refrigerating system.
