Sound production is not chemical change.
The molecular geometry is trigonal bipyramidal.
Answer : The formula of the gas produced is, 
(phosphine gas)
Explanation :
According to the question, when sodium phosphide is treated with water then it react to give phosphine gas and sodium hydroxide.
The balanced chemical reaction will be:
By Stoichiometry of the reaction we can say that:
1 mole of sodium phosphide reacts with 3 moles of water to give 1 mole of phosphine gas and 3 moles of sodium hydroxide.
Thus, the formula of the gas produced is, (phosphine gas)
Answer: Option C is correct
A polar molecule with nonpolar bonds
Explanation:
A polar molecule with nonpolar bonds cannot be polar because a polar molecule has net dipole that it has one end slightly positive and the other end slightly negative which allows the distribution of atoms .
Therefore it cannot have non polar bonds because non polar bonds allow electrons to be shared equally and it take place between non elemental substances or substances that are not elements , it cannot occur in elemental substances because these substances have different electronegativities which can be held by polar bonds alone.
