Explanation

Allotropes of carbon include diamond, graphite, fullerenes (such as buckminsterfullerenes or «buckyballs»), and carbon nanotubes.

Other allotropes also exist, such as graphene (single sheets of graphite), amorphous carbon, and carbyne.

These forms differ in the arrangement of their carbon atoms and, consequently, have distinct physical and chemical properties. 

Explanation

The main intermolecular force in NH₃ (ammonia) is hydrogen bonding.

This strongest type of intermolecular force that occurs

Because the hydrogen atoms in ammonia are bonded to the highly electronegative nitrogen atom,

Creating strong partial negative and positive charges that attract the hydrogen of one NH₃ molecule to the nitrogen of another. 

Explanation

A solid with a definite shape and volume is known as a Crystalline solid has a regular,

A repeating arrangement of particles that gives it a definite geometric form and a sharp melting point.

An Amorphous solid lacks this long-range order and does not have a fixed shape or geometric form.

A Liquid has a definite volume but takes the shape of its container,

A Plasma is an ionized gas with no definite shape or volume. 

Explanation

Diffusion is fastest in gases because gas particles are far apart and scurry, allowing them to spread out and mix quickly.

In contrast, particles in liquids move more slowly, and solids have tightly packed particles, making diffusion much slower.

Explanation

The universal gas constant R appears in the ideal gas law PV = nRT and has a value of 8.314 joules per mole per kelvin (J/mol·K) in SI units.  

Other values:  

- 0.0821 L·atm/mol·K is R in L·atm units  

- 1.987 cal/mol·K is R in calories  

- 9.8 m/s² is the acceleration due to gravity, not related to R

Explanation

The speed of light in a vacuum is approximately 3 × 10⁸ meters per second (m/s).  

This is a fundamental constant in physics, denoted by c, and is used in equations such as E = mc² and c = λ × f, where λ is wavelength and f is frequency.

Explanation

The formula for wave speed is wave speed = wavelength * frequency, so the product of wavelength and frequency represents the speed of a wave. 

Explanation

The period number represents the number of electron shells (energy levels) an element has.

For example, elements in period 2 have electrons in 2 shells.

Explanation

Across a period, the atomic number increases, meaning more protons in the nucleus.

- This results in a stronger attraction between the nucleus and the electrons.

- Since the electrons are added to the same energy level without much shielding, more energy is needed to remove an electron.

Explanation

Alkali metals are in Group 1 of the periodic table.

These elements are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).