Rare earth metals are a group of 17 elements - lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium - that appear in low concentrations in the ground
Answer:
currently model of the atom shows an atom that is mostly empty space. In the center is a small nucleus made of protons and neutrons. The nucleus contains nearly all the mass of an atom. Surrounding the nucleus is a cloud-like region with electrons moving too fast and too unpredictably for us to know their location
Explanation:
B is true because plants can only use nitrogen in the form of nitrates, no other living thing needs nitrogen therefore the percentage of nitrogen in the atmosphere is 79%
Answer:
The Answer is 88%
Explanation:
The balanced ionic equation of the reaction



Looking at the above reactions
The original number of moles of
= 3 × number of moles of 
= 3 × volume × concentration of
Note: The formula for number of moles is volume × concentration
mol
The number of moles of
left after its reaction with ascorbic acid
=
x moles of 
=
x volume x concentration of 

Note: The division by 1000 is to convert mill liter to liter
Moles of ascorbic acid = moles of
reacted



Hence
Mass of ascorbic acid = moles of ascorbic acid × molar mass of ascorbic acid


Weight% of ascorbic acid = mass of ascorbic acid/mass of sample x 100%
= 70.55/80 × 100%
= 88.1%
Answer:
<h2>18 kg.m/s</h2>
Explanation:
The momentum of an object can be found by using the formula
momentum = mass × velocity
From the question we have
momentum = 2 × 9
We have the final answer as
<h3>18 kg.m/s</h3>
Hope this helps you