Answer : The correct options are,
and 
Explanation :
Single displacement reaction : It is a type of chemical reaction in which the more reactive element displaces the less reactive element.
Option A reaction : 
It is an example of double displacement reaction because in this reaction a positive cation and a negative anion of the two reactants exchange their places to form two new products.
Option B reaction : 
It is an example of single displacement reaction.
Option C reaction : 
It is an example of combination reaction because in this reaction two reactants react to give a single product.
Option D reaction : 
It is an example of decomposition reaction because in this reaction a single reactant decomposes into two or more products.
Option E reaction : 
It is an example of single displacement reaction because in this reaction the most react element, aluminium displaces the less reactive element, hydrogen.
Hence, the options B and E are single displacement reactions.
In the given case, the scientist should use a circle graph or pie chart.
One can dissect a circle into smaller segments, a component of the circle is known as an arc and an arc is named on the basis of its angle. A pie chart, or a circle graph, is used to visualize data and information.
A circle graph is generally used to demonstrate the outcomes of an examination in a proportional way. In a circle graph, the arcs are proportional to how many percents of the population gave a particular answer.
Yes when a firework goes into the sky it releases chemical potential energy which is then changed into kinetic energy
Since monosaccharides are the simplest units of carbohydrates, then they are made up of carbon, hydrogen, and oxygen atoms.
empirical formula : CxH2xOx
where

Monosaccharides can be classified by the number x of carbon atoms they contain: triose(3) tetrose (4), pentose (5), hexose (6), heptose (7), and so on.