Answer:-
Metalloids
Explanation:-
The stair step line is a line in the periodic table that divides the metals on one side and the non metals on the other side. So the elements which lie on the stair step line must have properties in between those exhibited by the metals and those by the non metals.
Such elements we know are called metalloids. Thus In the periodic table, the elements that are adjacent to the "stair step" are called metalloids.
Answer:
1.25 gram of cesium-137 will remain.
Explanation:
Given data:
Half life of cesium-137 = 30 year
Mass of cesium-137 = 5.0 g
Mass remain after 60 years = ?
Solution:
Number of half lives passed = Time elapsed / half life
Number of half lives passed = 60 year / 30 year
Number of half lives passed = 2
At time zero = 5.0 g
At first half life = 5.0 g/2 = 2.5 g
At 2nd half life = 2.5 g/ 2 = 1.25 g
Thus. 1.25 gram of cesium-137 will remain.
0.086mole
Explanation:
The problem is very simple. It involves conversion from mass to number of moles of NaCl
What is mole?
A mole is a unit of measuring chemical substances. It is the amount that contains the avogadro's number of particles.
How is it related and can be converted from mass;
Number of moles of a substance = 
Since we know the mass, we can find the molar mass and put into this equation;
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Number of moles of NaCl = 
0.086mole
learn more:
Number of moles brainly.com/question/1841136
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The density of an object or quantity of matter is its mass divided by its volume.
