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.
The compound is basic in nature but the concentration substance is corrosive.
<h3>What is NaOH?</h3>
Sodium hydroxide is a compound that is formed from sodium and hydrogen as well as oxygen The compound is basic in nature but the concentration substance is corrosive.
a) The acute health effect of exposure to NaOH is skin burn while the chronic effect of exposure is damage to the lungs.
b) The first aid for the ingestion of NaOH is to take in plenty of water.
c) The compound is not flammable
d) The chemicals that could produce a dangerous reaction with NaOH are acids
e) To handle small spills, irrigate the affected area with plenty water and use lab coats, gloves and eye wear when working with the solution.
Learn more about sodium hydroxide:brainly.com/question/24010534
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Answer:
Zn+H2O ------ ZnO + H2 is the correct answer
The mass number plays an important role for elements and their isotopes. Mass number comes from the addition of protons and neutrons (their weight). Isotopes are the elements, but with a different number of neutrons. So in turn, by subtracting the number of protons (atomic number) from the mass, you can find the number of neutrons.