Question

What is the quark designation of a neutron?

	a.	uud.
	b.	ddd.
	c.	uuu.
	d.	udd.
	e.	ucb.

What happens to nuclei that have too many neutrons?

	a.	Extra neutrons β+-decay and turn into protons.
	b.	Extra neutrons α-decay and leave the nucleus.
	c.	Extra neutrons β−-decay and turn into protons.
	d.	Extra neutrons n-decay and leave the nucleus.

Answer 1

a>

Quarks are believed to be the basic building blocks of protons, neutrons and a wide variety of other, heavier particles, collectively called hadrons. Just as atoms are primarily composed of different combinations of protons, neutrons and electrons, hadrons are believed to be composed of different combinations of quarks. Quarks are usually thought of as elementary particles, i.e. particles that cannot be further broken down into other particles by any known means.

The currently accepted theory of elementary particles predicts that there should be six different kinds of quarks, designated by the letters u (for 'up' quark), d (down), s (strange), c (charmed), b (bottom or beauty), and t (top or truth). The lightest quarks are the 'up' and 'down' quarks, which compose the more common, 'ordinary' particles like protons and neutrons. The 'up' and 'down' quarks are assigned an electric charge or +2/3 of the electronic charge and -1/3 of the electronic charge, respectively. Because no free particles have ever been observed with a charge equal to a fraction of an electronic charge, the quarks must combine in groups of three.

neutons are denoted by udd.

those nuclei which have too many neutrons, these neutrons convert into proton to attain nucleus stability, this reaction can be shown as -

0 n 1 ------> 1 p 1 + -1 0 + neutrino

so it can be said that extra neutrons get into beta minus decay and turn into protons.