Please need help on this

Consider the nuclear equation below. 239/94 pu—-> x+ 4/2 he. what is x?

Which set of characteristics best describes igneous rock? a) largest type of rock, made of organic matter, hardest type of rock b) least abundant type of rock, made of other rocks, made mostly of minerals c) found on all continents, contains wavy bands of stripes, contains fossils d) most abundant type in earth's crust, made of magma/lava, contains no fossils

Avariable that is not being directly tested during an experiment should be