We know
[tex]\boxed{\Large{\sf M_1V_1=M_2V_2}}[/tex]
[tex]\\ \Large\sf\longmapsto M_2=\dfrac{M_1V_1}{V_2}[/tex]
[tex]\\ \Large\sf\longmapsto M_2=\dfrac{3(75)}{250}[/tex]
[tex]\\ \Large\sf\longmapsto M_2=\dfrac{225}{250}[/tex]
[tex]\\ \Large\sf\longmapsto M_2=0.9M[/tex]
Answer:
Mass 1=3M
Mass 2=?
Volume1=75mL
Volume2=250mL
By using molarity formula:
mass1*volume 1=mass2*volume 2
3M*75=mass2*250
mass2=225/250
mass2:0.9M