That prediction is not correct because Xenon is extremely stable; column 18 of the periodic table contains the noble gasses, which are stable because their outer-most energy levels are completely filled. Having the octet (8) of valence electrons means that the element no longer needs to lose or gain electrons to gain stability.
The column 17 elements are unstable because they only have one valence electron short of the stable octet configuration of the noble gasses.
How can I help? What’s the question?
<u>Answer:</u>
<em>The average speed of the car is 66.9 km/h</em>
<u>Explanation:</u>
Here distance covered with the speed <em>57 km/h=7 km </em>
distance covered with the speed of <em>81 km/h=7 km</em>
<em>Average speed is equal to the ratio of total distance to the total time.
</em>
<em>total distance= 7 + 7= 14 km </em>
<em>
</em>
<em>time taken to cover the first 7 km= 7/57 h </em>
<em>time taken to cover the second part of the journey = 7/81 h
</em>
<em>average speed =
</em>
<u><em>Shortcut:
</em></u>
<em>When equal distances are covered with different speeds average speed=2 ab/(a+b) where a and b are the variable speeds in the phases.
</em>