Science 4

What are the 2 changes we've studied so far?

Answer explanation

Physical and chemical changes

Which one does not change the chemical composition or nature of the substance?

• Physical change

• Chemical change

Are the physical changes reversible or non-reversible?

• Reversible

• Non-reversible

Answer explanation

Remember water and ice. You can melt ice into water and then freeze it again.

Which are physical changes? You can choose more than one answer.

• Change of state

• Dissolution

• Deformation

Wich one of the sentences is correct for chemical changes ?

• Not easily reversible

• Dissolution

• Dissolving a solute in a solvent

Answer explanation

Reversible only through chemical means or reactions

Presence of air, light, water and salt can accelerate this change

• Combustion

• Cellular respiration

• Photosynthesis

• Oxisation

Which sentence is true ?

• The atom contains a very dense and very small nucleus

• The atom contains electrons that rotale around a nucleus

• The atom is essentially vacuum

Which of the following statements are false ?

• Iodine is a halogen with five electron layers

• Beryllium (B), is an alkaline-earth metal in the second period of the periodic table

• Potassium is a metal in the third perio of the period table

• Oxygen is a gas in the second period of the periodic table

Organize these options into the right categories

Groups:

(a) Oxidation

,

(b) Combustion

,

(c) Phtosynthesis

,

(d) Cellular respiration

• Decomposition is one type of this chemmical change

• Reaction with oxygen

• Fuel : promote this chemical change

• Releases a large amount of energy

• Animal cells use glucose and oxygen to create energy

• To prevent or slow this change, galvanize the metal

• Chemical change that produces glucose and oxygen from solar energy, carbon dioxide and water

• Presence of air, light, water and salt can accelerate this change

True ou False : Electrons are positively charged and protons are negatively charged?

• True

• False

Answer explanation

The opposite is true