Answer:
Option A
Explanation:
Silicon (Obtained from Sand (SiO2)) is the element that is primarily used in appliances to make electronic chips.
Answer:
Three hydrogen atoms to form PH₃.
Explanation:
Hello!
In this case, since the elements belonging to the nitrogen family (N, P, As, Sb and Bi) show five valence electrons, because there are five electrons at their outer shell, it is clear that if phosphorous bonds with hydrogen, it is going to require the same amount of oxygen atoms (3) because elements having five valence electrons need 3 bonds in order to attain the octet (5+3=8).
Therefore the compound would be:

Which is phosphine.
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Answer: While there is no cure for Down Syndrome, there are therapies, treatments, and educational support available to improve the quality of life of those affected. The exact course of treatment will depend on the individual, taking into account the person’s age, overall health, environment, and personal strengths and limitations. Some example of therapies available are: speech-language therapy, physical therapy, occupational therapy, and assistive technology.
Answer:they are used to generate sound waves in the ultrasonic range
Explanation:transducers are used to generate sound waves in the ultrasonic range ,by turning electrical energy into sound