Which of these are not mechanical waves and can be used to send a signals to satellites orbiting the earth? a) sound waves b) radio waves c) both sound waves and radio waves d) neither sound waves or radio waves

Mechanical waves require a medium to travel. These types of waves transfer energy through vibrations of the medium particles. The medium particles compress and decompress i.e. the wave moves forward carrying energy through compressions and rarefactions. Sound waves are mechanical waves. On the other hand, radio waves are electromagnetic waves and can travel through vacuum as well. Radio  waves have frequency from 30 Hz- 300 GHz. Hence, Radio signals are used to send signals to satellites orbitting Earth.

Correct ans is (B).

The sound wave is a mechanical wave, and it require a medium to travel their energy from one position to another. Whereas Radio wave is an electromagnetic wave, it can travel through any medium-be it air, a solid material or vacuum.  

To carry satellite signals Radio waves are used and Radio waves travel at the speed of light ( i.e, 300,000 km/s). To send and receive radio signals for television, phone or internet communications are used communications satellites. Longer wavelength radio waves are reflected from an electrically charged layer of the upper atmosphere.  

  the grams     of oxygen gas   that can be produced     is 20.6   grams of o₂

calculation

2liclo₃ →   2 licl + 3 o₂

step 1:   find the moles of liclo₃

moles = mass÷ molar mass

from periodic table the molar mass of liclo₃ =6.9 +35.5   +(16 x3) =90.4 g/mol

moles=38.7 g÷90.4 g/mol=0.4281   moles

step 2:   use the   mole ratio   to calculate the moles of o2

from equation above, liclo₃: o₂   is 2: 3  

therefore the moles of   o₂=0.4281 moles x3/2 =0.6422   moles

step 3: find mass   of o₂

mass= moles x molar mass

from periodic table the   molar mass of   o₂ = 16 x2= 32 g/mol

mass=0.6422   moles   x   32 g/mol = 20.6 grams of o₂

neither accurate nor precise.