Answer:
B. Line 2 has a mistake
Explanation:
1. All electromagnetic waves are made of both electric and magnetic fields (hence the name electromagnetic).
2. All electromagnetic waves are transverse, and not longitudinal.
3. All electromagnetic waves can travel through space because they do not need particles to travel (like sound waves).
4. Electromagnetic waves all travel at the speed of light (299 792 458 m/s).
Answer : The correct option is, (a) Synthesis
Explanation :
Synthesis reaction : A chemical reaction where multiple substances or reactants combine to form a single product.
It is represented as,

Combustion reaction : A chemical reaction in which a hydrocarbon react with the oxygen to give product as carbon dioxide and water.
It is represented as,

Single replacement reaction : A chemical reaction in which the more reactive element replace the less reactive element.
It is represented as,

In this reaction, A is more reactive element and B is less reactive element.
Double replacement reaction : It is a type of chemical reaction where a positive cation and a negative anion of two reactants exchange places to form two new products.
It is represented as,

(X and A are the cations, Y and B are the anions)
The given reaction is, 
In this reaction, calcium combine with the chloride to form calcium chloride as a product.
Hence, the given type of reaction is a synthesis reaction.
Answer:
Volume of the cube is 2*2*2 = 8cm^3.
Divide the weight (40g) over the volume (8cm^3).
Density is 5g/cm^3. Definitely not gold.
Explanation:
Answer:
The first and last choice
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