The correct answer is D.
Echo refers to the sound that is heard when a sound wave is reflected back from a surface. An echo sound is made when a sound wave traveled through the air, hit a hard surface and get reflected back. Generally, hard surfaces reflect sound wave while soft surfaces absorb sound waves. Reflected sound waves are used in application of some devices that are used in range and direction finding.
Silver is not a compound. It's a mixture
When air pressure is low it is Cold
Close all network ports, filter those you can't block
Firewalls are used to filter network traffic and are available as standard system software on most operating systems. Limit the openings hackers have to your server.
<span>Ag2S
Ag(silver) has a charge of 1+
S2-(Sufide has a charge 2-
you need balance
charge have to equal to zero so you need 2 silvers and one sulfide
to have equilibrium</span>
