If the celsius temperature of a gas at constant pressure is increased from 10 celsius to 20 celsius the volume is

               The volume is increased.

Explanation:

                     According to Charles' Law, " at constant pressure the volume and temperature of the gas are directly proportional to each other". Mathematically this law is presented as;

                                                    V₁ / T₁ = V₂ / T₂   (1)

In statement the data given is,

T₁  =  10 °C  =  283.15 K                    ∴  K  =  273.15 + °C

T₂  =  20 °C  =  293.15 K

So, it is clear that the temperature is being increased hence, we will find an increase in volume. Let us assume that the starting volume is 100 L, so,

V₁  =  100 L

V₂  =  Unknown

Now, we will arrange equation 1 for V₂ as,

                                                    V₂  =  V₁ × T₂ / T₁

Putting values,

                                     V₂  = 100 L × 293.15 K / 283.15 K

                                     V₂  = 103.52 L

Hence, it is proved that by increasing temperature from 10 °C to 20 °C resulted in the increase of Volume from 100 L to 103.52 L.