The model of the atom has dramatically changed over many many years.We learned atoms make up different substances and are the smallest particles of matter, which have subatomic particles that are very small portions of matter. At first scientist only thought there were electrons which are negatively charged.
Answer : The balanced chemical equation is,
Explanation :
Balanced chemical equation : It is defined as the number of atoms of individual elements present on the reactant side must be equal to the number of atoms of individual elements present on product side.
The given unbalanced chemical reaction is,
This chemical reaction is an unbalanced reaction because in this reaction, the number of atoms of individual elements are not balanced.
In order to balanced the chemical reaction, the coefficient 2 is put before the 
, the coefficient 3 is put before the 
and the coefficient 4 is put before the 
.
The energy evolved in this reaction = 
Thus, the balanced chemical reaction will be,
The answer is: II.The endpoint is recorded when the solution is dark red in color rather than light pink.
The endpoint is the point at which the indicator changes colour in a colourimetric titration and that is point when titration must stop.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions. If this indicator change color to dark red, more base is added and endpoint is not accurate.
If the the acid is spilled before titration, that does not make endpoint wrong and molar mass can be calculated.
In this example we can take acetic acid as carboxylic acid; basic salt sodium acetate CH₃COONa is formed from the reaction between weak acid (in this example acetic acid CH₃COOH) and strong base (in this example sodium acetate NaOH).
Balanced chemical reaction of acetic acid and sodium hydroxide:
CH₃COOH(aq) + NaOH(aq) → CH₃COONa(aq) + H₂O(l).
Neutralization is is reaction in which an acid (in this example vinegar or acetic acid CH₃COOH) and a base react quantitatively with each other.
That's because the first and last carbon atoms cannot be branched to form an isomer . Therefore only the three middle carbon atoms can form isomers.
Answer:Hydrogen is placed such because it exhibits some similar characteristics of both group1 and group VII elements.
Explanation:
The reason why hydrogen is similar to group 1 metals:
#It has same valence electron and inorder achieve octet state it can lose that electron and forms H+ ion
#It acts as a good reducing agent similar to group1 metals
#It can also halides
Similarity to halogens:
#hydrogen can also gain one electron to gain noble gas configuration. It can combine with other non metals to form molecules with covalent bonding.
#It exists as diatomin molecule,H2
#Have the same electronegativity nature
#its reaction with other metal
