Answer:
A. a new substance is being produced.
Explanation:
The bubbles most likely indicates that a new substance is being produced by this reaction. In essence, we describe this sort of change as chemical change.
In a chemical change, new substances are usually produced. They are accompanied by the evolution or absorption of energy.
The reaction of Zinc with a strong acid to produce bubbles on the surface of the metal indicates a chemical change and the formation of a new kind of substance.
Take for example, let zinc reacts with hydrocholoric acid, HCl;
Zn + 2HCl → ZnCl₂ + H₂
Since Zn is higher than Hydrogen in the activity series, it will displace it from HCl and liberate hydrogen gas as a product. This will cause the bubbles observed in the reaction.
This is a chemical change and new products have been formed.
B and D are wrong because they are both physical changes.
C is wrong because no information about such is provided by the problem statement.
So, when a piece of zinc metal combines with a strong acid, a new kind of substance is produced.
The fusion reaction in the sun is a combination of hydrogen atoms fusing to create helium. The fusion reaction in larger stars involve much heavier elements like oxygen and iron. In supernovas, often elements like gold are produced
Answer: Option (B) is the correct answer.
Explanation:
- An ionic bond is formed by the sharing of electrons between two chemically combining atoms.
In an ionic bond, there occurs attraction between oppositely charged ions due to which there occurs strong forces of attraction between them. Therefore, ionic bonds are the strongest bonds.
- A polar covalent bond is formed due to unequal sharing of electrons between the combining atoms.
For example, 
is a polar covalent compound. Partial opposite charges tend to develop on the atoms of a polar covalent compound.
- A non-polar covalent bond is formed due to equal sharing of electrons between the combining atoms.
For example, 
is a non-polar covalent molecule. No partial charges will be there on the atoms of a non-polar covalent molecule.
- A hydrogen bond is defined as the bond formed between a hydrogen atom and an electronegative atom.
For example, in HCl compound there occurs hydrogen bonding.
In this type of bond, dipole-dipole attractive interactions tend to take place. And, strength of hydrogen bonds is very weak.
Thus, we can conclude that given bond types are arranged in order of increasing strength as follows.
Hydrogen bonds < non-polar covalent bonds < polar covalent bonds < ionic bonds
Answer:
<u>When small organic molecules bind together, they form larger molecules called biological macromolecules.</u>Biological macromolecules are important cellular components and perform a wide array of functions necessary for the survival and growth of living organisms. The four major classes of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids.
(i hope this helps)
