Alkali metals: left column of your periodic table (not hydrogen, but anything below it). They have one valence electron, which they are happy to share in a reaction.
Halogens: second column from the right of your periodic table. They are one electron short of a full shell, so they are reactive in the opposite way that alkalis are--they want electrons.
Atomic number (number of protons) is the big number on the periodic table square. Hydrogen's is 1.
Atomic mass is a little number down below. For example, Hydrogen's is 1.008.
Neutrons are a tricky subject, because different isotopes of the same element can have different numbers of neutrons. You can't generally get this from the atomic mass, because the atomic mass is a weighted average of naturally occurring isotopes. Hydrogen can have 0,1, or 2 neutrons. To answer this, you'd have to choose a particular isotope from the table of isotopes (a completely different chart from the periodic table) which has a certain number of neutrons: n = weight - Z.
Valence electrons are the electrons in the outermost shell. (The column of the table).
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Number of principal shells is the row of the periodic table. </span>
Photons are particles of electromagnetic radiation.
Answer:
Explanation:
= Length of wire = 65 m
= Initial current = 1.8 A
= Final current = 2.9 A
We know
and
so
The length of the wire remaining on the spool is .
Answer:
✓ A cyclone device accumulates fine particulates from the air by making a dirty air stream flow in a spiral path inside a cylindrical chamber.
✘ It consists of several long and narrow fabric filter bags suspended upside-down in a large enclosure.
✓ When dirty air enters the chamber, the larger particulates strike the chamber wall and fall into a conical dust hopper at the bottom.
✘ Fans blow dirt-filled air upward from the bottom of the enclosure, trapping dirt particles inside the filter bags and releasing clean air from the top.
✓ The top of the chamber has an outlet that lets out cleaned air.
Basically, any of these choices that have the word "filter" are wrong. The point of the cyclone device is to separate the particles without the use of filters. You can tell the right answers based on the picture attached below.
