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3 years ago

People can hear ultrasound easily. A. True B. False

1 answer:

3 0

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. ... Ultrasound is used in many different fields.

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The diagram shows the electron arrangement in a molecule of ammonia, showing only outer

rusak2 [61]

Answer:

Since this is old, im just gonna get these points, don't wan't them to go to waste lm.ao

Explanation:

3 0

3 years ago

All the substances listed below are fertilizers that contribute nitrogen to the soil.

kvv77 [185]

Answer:

Ammonia is the richest source of nitrogen on a mass percentage basis because it has 82.35% of nitrogen by mass.

Explanation:

Percentage of element in compound :

$=\frac{\text{number of atoms}\times text{Atomic mass}}{\text{molar mas of compound}}\times 100$

(a) Urea, $(NH_2)_2CO$

Molar mass of urea = 60 g/mol

Atomic mass of nitrogen = 14 g/mol

Number of nitrogen atoms = 2

$N\%=\frac{2\times 14 g/mol}{60 g/mol}\times 100=46.67\%$

(b) Ammonium nitrate, $NH_4NO_3$

Molar mass of ammonium nitrate = 80 g/mol

Atomic mass of nitrogen = 14 g/mol

Number of nitrogen atoms = 2

$N\%=\frac{2\times 14 g/mol}{80 g/mol}\times 100=35.00\%$

(c) Nitric oxide, NO

Molar mass of nitric oxide = 30 g/mol

Atomic mass of nitrogen = 14 g/mol

Number of nitrogen atoms = 1

$N\%=\frac{1\times 14 g/mol}{30 g/mol}\times 100=46.67\%$

(d) Ammonia, $NH_3$

Molar mass of ammona = 17 g/mol

Atomic mass of nitrogen = 14 g/mol

Number of nitrogen atoms = 1

$N\%=\frac{1\times 14 g/mol}{17 g/mol}\times 100=82.35\%$

Ammonia is the richest source of nitrogen on a mass percentage basis because it has 82.35% of nitrogen by mass.

4 0

3 years ago

This diagram shows the forces acting on a car. The center dot represents the car, and the arrows represent the forces acting on

Mariulka [41]

Answer : The correct option is B- Towards the left.

Solution : Given,

Force on car in upward direction, $F_1$ = 6000 N

Force on car in downward direction, $F_2$ = 6000 N

Force on car in right direction, $F_3$ = 5000 N

Force on car in left direction, $F_4$ = 6000 N

Force : Force is equal to the mass multiplied by the acceleration. The force is directly proportional to the acceleration.

Formula : F = m × a

where, F is force, m is mass and a is acceleration.

From the given diagram we conclude that the $F_1$ and $F_2$ are in opposite direction and the force acting on car are same. So, their net force is zero.

And in case of $F_3$ and $F_4$ , the net force will not be zero because force acting on car are different. The car will accelerate towards left direction because $F_4$ is higher than the $F_3$ .

So, the car will accelerate towards left direction.

3 0

3 years ago

The carbon-carbon double bond in ethene is ________ and ________ than the carbon-carbon triple bond in ethyne.

lbvjy [14]

Answer:

weaker and longer

Explanation:

Since there are 3 bonds in ethyne in comparision with the 2 bonds of ethyne between carbon atoms, they are attracted more to each other → the bond gets shorter . And since there are one more bond that supports the union → the bond gets stronger

thus the carbon-carbon double bond in ethene is weaker and longer than the carbon-carbon triple bond in ethyne

3 0

3 years ago

Um...id.k how to do chemistry...help please?

qaws [65]

Answer:

NaBr

Explanation:

3 0

3 years ago

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