Answer:
The anwer is not D the anwer is A
Explanation:
When you add a pinch of baking soda into vinegar, carbon dioxide gas is produced
Answer:
Elements in same column of periodic table have same properties.
Explanation:
The elements in the same group have same number of valance electrons thus have similar properties.
Consider the elements of group two i.e alkaline earth metals. All have two valance electrons and show similar properties.
Magnesium, barium, calcium etc.
All alkaline earth metals form salt with halogens.e.g,
Mg + Cl₂ → MgCl₂
Ba + Br₂ → BaBr₂
Mg + Br₂ → MgBr₂
Ca + Br₂ → CaBr₂
They react with oxygen and form oxides of respective metal.
2Mg + O₂ → 2MgO
2Ba + O₂ → 2BaO
2Ca + O₂ → 2CaO
these oxides form hydroxide when react with water,
MgO + H₂O → Mg(OH)₂
BaO + H₂O → Ba(OH)₂
CaO + H₂O → Ca(OH)₂
With nitrogen it produced nitride,
3Mg + N₂ → Mg₃N₂
3Ba + N₂ → Ba₃N₂
3Ca + N₂ → Ca₃N₂
With acid like HCl,
Mg + 2HCl → MgCl₂ + H₂
Ba + 2HCl → BaCl₂ + H₂
Ca + 2HCl → CaCl₂ + H₂
It can be separated by physical means and is not uniform in composition.
Answer: Option (3) is the correct answer.
Explanation:
A reaction due to which there occurs change in chemical composition of reactants is known as a chemical reaction.
For example, evolution of heat when two substances combine together shows a chemical reaction has taken place between the substances.
Whereas a reaction which does not bring any changes in chemical composition of the reactants is known as a physical reaction.
For example, boiling point, melting point, mass, volume etc are all physical properties.
Thus, we can conclude that out of the given options a substance melts when sitting in the Sun, is not an indication of a chemical reaction.
