Nonane (b) has the highest melting point.
-----------------------------
A caveat: I'm assuming that we're dealing with the straight-chain isomers of these alkanes (specifically pentane and nonane). The straight-chain isomer of pentane (<em>n</em>-pentane, CH3-[CH2]3-CH3) has a melting point of -129.8 °C; the straight-chain isomer of nonane (<em>n-</em>nonane, CH3-[CH2]7-CH3) has a melting point of -53.5 °C. The pattern holds as you go down (or up): The more carbon atoms, the higher the melting point. So, in decreasing order of melting points here, you'd have the following: nonane > pentane > butane > ethane.
However, one structural isomer of pentane, neopentane, has a melting point of -16.4 °C, which is <em>higher </em>that the melting point of <em>n</em>-nonane despite neopentane having the same molecular formula as its straight-chain isomer. Of course, you're not to blame for coming up with this question; this is just some extra info to keep in mind.
Answer:
3Ba(OH)₂ + 2H₃PO₄ → Ba₃(PO₄)₂ + 6H₂O
Explanation:
Neutralization reaction:
When an acid and base react they form water and salt.The reaction is called neutralization reaction.
General equation:
HX + BOH → BX + H₂O
From given reaction equations only option C is correct because only this reaction gives salt and water.
Chemical equation:
3Ba(OH)₂ + 2H₃PO₄ → Ba₃(PO₄)₂ + 6H₂O
Barium hydroxide is acting as a base. H₃PO₄ is an acid. Both these reactants react to form salt which is barium phosphate and water.
Other options are incorrect because non of these reaction produced salt and water. So option A is correct.
D) to keep as many things the same as possible across the parts of an experiment.
Answer:
64g of 
44.8L
vapour density of 
of 
=64/44.8=10/7=1.43 g/l
Vapour density of =1.43g/l
