For average speed, we divide the total distance covered by the total time taken.
After doing that, you will see that Jane has the lowest average speed.
C. Distance from Earth
The observed brightness of a star (the apparent magnitude) to an absolute magnitude, you need to know the distance [d], to the star. Alternatively, if we know the distance and the apparent magnitude [m] of a star, we can calculate its absolute magnitude [d].
*paraphrased from "COSMOS.com"
Answer : (C) Hafnium is the most likely identity of the given substance.
Solution : Given,
Mass of given substance (m) = 46.9 g
Volume of given substance (V) = 3.5 
First, find the Density of given substance.
Formula used :

Now,put all the values in this formula, we get
= 13.4 g/
So, we conclude that the density of given substance (13.4 g/
) is approximately equal to the density of Mercury and Hafnium (13.53 and 13.31 g/
respectively).
According to the question the substance is solid at room temperature but Mercury is liquid at room temperature. So, Mercury is not identical to the given substance.
Another element i.e, Hafnium is the element whose density is approximately equal to the given substance and also solid at room temperature. And we know that the melting point of solid is high.
So, Hafnium is the most likely element which is the identity of the given substance.
Answer: The given statement is true.
Explanation:
Water is a natural resource present in the nature and it is very precious as life without it is impossible.
So, when we unnecessarily use water then it means we are wasting a natural resource that cannot be reproduced again by human beings.
Therefore, more we are able to conserve water more we can protect other human life's and environment also.
If there is shortage of water then its prices will go high and hence we need to pay more for it.
Thus, we can conclude that the statement conserving water can save money while protecting the environment, is true.
Answer: Option B
Explanation: when strong acid react with strong base, the resulting solution is neutral as in the case of HCl and NaOH
HCl + NaOH —> NaCl + H2O
From the equation obtained, The salt ( NaCl) obtained is a normal salt which is neutral.