B) hydrogen gas burns in air.
explanation: the rest are physical properties.
Lanthanide belongs to period 6, and actinides belongs to period 7
Answer:
See explanation
Explanation:
Polymerization is the process whereby two or more monomers link together to form a compound of high molecular mass called a polymer.
There are two kinds of polymers;
-Addition polymers
-Condensation polymers
Addition polymers are formed by the joining of two or more monomers to form a polymer without the elimination of a small molecule.
Condensation polymers are formed by the joining of two or more molecules to form polymers with the elimination of a small molecule.
The main difference between polyethene and polyester is that polyethene is an addition polymer while polyester is a condensation polymer.
In polyethene, ethene molecules are joined together having the repeating unit as [-CH2-CH2-]n.
In polyester, the polymer arises from the reaction of carboxylic acid and an alcohol and loss of water molecules.
46.6% Oxygen
27.7% Silicon
8.1% Aluminium
5.0% Iron
3.6% Calcium
2.8% Sodium
2.6% Potassium
2.1% Magnesium
increase the force needed to move the object
Explanation:
If a machine decreases the distance an object moves, it must also increase the force need to move the object.
A machine is a device that is used to do work with a little energy input.
Work done = force x distance
We see that to do more work, a lot of force must be applied to move a body through a greater distance.
If the distance is reduced;
Distance = 
More force must be applied to measure up for the distance and make the machine more efficient.
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