<span>The scientists discovered that when they organized elements in order of increasing atomic mass there is a pattern of repetition of properties (A). The periodic law was developed by Dmitri Mendeleev and Lothar Mayer in 1869. They worked independently of each other and both created a periodic table. They both arranged the items on the table by weight and both suggested that certain properties of the elements recur. The Mendeleev table is the most important table because the values for the atomic mass are the most accurate.</span>
This statment is false, the pen on a seismograph does not swing freely.
the answer to your question is
M1V1=M2V2
V2=750-150=600 ml
0.75M*750 ml = M2*600
M2=0.75*750/600 ≈ 9.38 M
B)The concentration of the acid (C₁) is the same as that of the base (C₂).
V₁=V₂
n(acid)=C₁V₁
n(base)=C₂V₂
HX + YOH = YX + H₂O
n(acid)=n(base)
C₁V₁=C₂V₂
C₁=C₂