Explanation

One up quark and two down quarks, when combined, make a neutron. 

More specifically:

A proton consists of two up quarks and one down quark (uud). 

A neutron consists of one up quark and two down quarks (udd). 

An electron and a positron are elementary particles, not composed of quarks. 

Explanation

 To calculate the bond order of O2²⁻, we need to construct a molecular orbital diagram.

The molecule has 18 electrons (12 from oxygen atoms and 6 from the negative charge).

These electrons are filled into the orbitals, starting from the lowest energy level. 

Explanation

 p24:

This protein is part of the Gag protein complex, which is responsible for forming the viral core.

The matrix is the layer surrounding the viral core, and p24 is the primary structural component of this matrix. 

gp120 and gp41:

These are glycoproteins on the surface of the HIV envelope.

They are involved in viral attachment to and entry into host cells, but not the formation of the matrix. 

Explanation

 The sex of a baby is determined by the sperm that fertilizes the egg.

If the sperm carries a Y chromosome, the baby will be a son.

If the sperm carries an X chromosome, the baby will be a daughter.

Since the chances of receiving a Y or an X chromosome are roughly equal, the probability of having a son or a daughter is approximately 50/50, or 1:1. 

Explanation

They can be reshaped – False.

While cartilage is flexible, it does not permanently change shape without surgical intervention or long-term external force (like in orthodontics or ear reshaping).

It’s not inherently reshaping like soft tissues.

Explanation

1-Butyne is an alkyne, and the hydrogen atom attached to the triple-bonded carbon is relatively acidic due to the high s-character of the carbon involved in the triple bond.

This allows it to donate a proton (H+) in an acid-base reaction. 

Explanation

At the highest point of a projectile's motion:

- Its velocity is purely horizontal (vertical component = 0).

- Its acceleration is still vertically downward due to gravity.

So, the velocity vector is horizontal, and the acceleration vector is vertical ⇒ they are perpendicular.

∴ Angle between velocity and acceleration = 90°  

Explanation

The heavily doped region of a transistor is called the emitter.

The emitter's heavy doping ensures it injects a large number of charge carriers (electrons in NPN transistors, holes in PNP transistors) into the base region, which is crucial for the transistor's operation. 

Explanation

 A "hybrid" refers to an organism that has inherited different alleles for a trait from each parent, making it heterozygous.