Question

Tomato juice acidic or basic?

Answer 1

Acidic nature and basic nature of compounds is defined in many ways starting from Arrhenius theory, Lewis acid base or Bronsted Lowry theory. Acidity and basicity are inherent properties of any molecule which is tested or determined by using various indicators like litmus paper, phenolphthalein.

Complete answer:
According to primitive knowledge of chemistry acid and bases are distinguished based on their taste but later a number of parameters are discovered to distinguish acid and base.

PROPERTY	ACID	BASE
Based on taste	sour
According to Arrhenius	Generate hydrogen ion in aqueous medium	Generate hydroxide ion in aqueous medium
According to Bronsted lowery	They are hydrogen ion donor	They are hydrogen ion acceptor
According to Lewis concept	They are electron pair acceptor	They are electron pair donor
Ph range	$1 - 7$	$8 - 14$
Product water hydrolysis	Hydronium ion	Hydroxide ion
Reactivity with various metals	Release hydrogen gas	No hydrogen gas released
Physical appearance	Do not give soapy feel	Soapy feel
Litmus changes	Red litmus converts into blue in colour	blue litmus converts into red in colour
Synthetic indicator	Methyl red, methyl orange	Phenol red, thymol blue
Natural examples	Tomato juice, lemon juice	Baking soda,
Synthetic examples	Hydrochloric acid, sulphuric acid, citric acid, malic acid	Soap, sodium hydroxide, potassium hydroxide, aluminium trichloride.

Basic constituents of tomato juice are citric acid and malic acid which impart sour taste to tomato juice therefore it comes under the category of acid.
$\Rightarrow$ Tomato juice is acidic in nature.

Note:
Each theory has some limitations like Arrhenius was unable to explain the acidic and basic nature of compounds in non-aqueous conditions. Lowery and Bronsted concept of acid base theory was unable to explain nature of some compounds like $B{F_3},AlC{l_3}$.Similarly, Lewis was unable to explain the strength of various acids and bases.