False, Carbon usually forms four covalent bonds.
Answer:
Son aquellas ondas que no necesitan un medio material para propagarse. Incluyen, entre otras, la luz visible y las ondas de radio, televisión y telefonía. Todas se propagan en el vacío a una velocidad constante, muy alta (300 0000 km/s) pero no infinita.
Sound waves need to travel through a medium such as solids, liquids and gases. The sound waves move through each of these mediums by vibrating the molecules in the matter. The molecules in solids are packed very tightly. Liquids are not packed as tightly. And gases are very loosely packed. This enables sound to travel much faster through a solid than a gas. Sound travels about four times faster and farther in water than it does in air.
Light waves do not require a medium to travel. This is how light can travel through space and we can see stars. Light waves travel at a much higher velocity as compared to sound waves. The velocity of light waves (through a vacuum) is 3 xx 10^8 m/s. In comparison, the velocity of sound waves (in air) is about 343 m/s. Different frequencies of light waves give rise to different colors. On the other hand, different frequencies of sound waves result in different pitches. Light waves and sound waves have very different frequencies from each other. Sound waves have low frequencies (20 to 20,000 Hz) as compared to light waves (~ 10^14 Hz).
Choice-'b' says the formula for kinetic energy in words.
KE = (1/2) · (M) · (S²)
The answer to your question is: the lungs.
The lungs allow the respiratory system to take in oxygen.
(Hope this helps!)
