Required Heat = Q

Q = Mass * specific heat of water * change in temp.

Q = 5g * 1g/cal*degC * 20degC

Q = 100 cal of heat is required

To convert calories to Joules,
1 cal = 4.184 Joules

100cal = 418.4 J of heat is needed

5 0

3 years ago

When an excited electron falls from n = 3 to n = 2, a red radiation in the Balmer series emitted. What is the frequency of this

vichka [17]

Answer:

The frequency of this photon is $4.57\times10^{14}\ Hz$

(D) is correct option.

Explanation:

Given that,

Excited states,

$n=3$

$n=2$

We need to calculate the wavelength

Using formula for energy

$E=13.6(\dfrac{1}{n^2}-\dfrac{1}{m^2})$

$E=13.6(\dfrac{1}{4}-\dfrac{1}{9})$

$E=1.888\ eV$

$E=1.888\times1.6\times10^{-19}\ J$

$E=3.0208\times10^{-19}\ J$

We need to calculate the frequency

Using formula of frequency

$E=hf$

$f=\dfrac{E}{h}$

Where, E =energy

$f=\dfrac{3.0208\times10^{-19}}{6.63\times10^{-34}}$

$f=4.57\times10^{14}\ Hz$

Hence, The frequency of this photon is $4.57\times10^{14}\ Hz$

4 0

3 years ago

A car is travelling at 20m/s, accelerates at 4m/s2 . Calculate its velocity after 5s?

IgorLugansk [536]

Answer:

Explanation:

The final velocity of an object that experiences a period of acceleration is given by:

v - vi = A*t

Initial velocity, vi, is = 20m/s

Acceleration, A, is 4m/2^2

Time, t, is 5 seconds

v - vi = A*t

v - 20m/s = (4m/2^2)/(5 sec)

v = (20 m/s) + (20 m/s)

v = 40 m/s

5 0

2 years ago

When you mix two gases what can you predict about the conservation of volume in this case?

o-na [289]

Amagat's law of additive volumes states that we can simply add up the individual volumes of each gas (provided they are at the same temperature and pressure) to get the total volume of the mixture. Conservation of volume is an acceptable assumption for gases (but not always for liquid mixtures). This works for gases since the molecules are very small and only take up a minimal amount of space in a gas.

3 0

3 years ago