Which of the following equations has correct formulas and also is a balanced equation?

a.
caco3 --> cao + co3

b.
2be + o2 --> 2beo

c.
mg + o2 --> mgo2

d.
3kcl + hno3 --> 3hcl + kno3

Answer : The correct option is, (B)

Explanation :

Balance equation : Balanced equation are those equation in which the number of atoms of each element and the total charge must be same on products side and reactants side.

In the given options, only option (B) equation has correct formula and also a balanced equation.

while the other options has incorrect formulas and also an unbalanced equations.

The correct equation for option A is,

The correct equation for option C is,

The correct equation for option D is,

Hence, the correct answer is, (B)

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

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