Answer:
Step-by-step explanation:
Alright, lets get started.
Suppose they take t minutes to meet each other.
Distance covered by first friend in t minutes, = 0.2 *t=0.2∗t
Distance covered by second friend in t minutes , =0.15 *t=0.15∗t
Total distance is given as 7, so
0.2 t + 0.15 t = 70.2t+0.15t=7
0.35 t = 70.35t=7
t = 20t=20
means after 20minutes they will meet.
SO. the average speed is 10m: Answer
Answer:
The period 4 alkaline-earth metal has the name Calcium. An isotope of this element having 20 neutrons has a mass number of 40.
Explanation:
Looking at the periodic table 4th row for the alkaline-earth metal, we can find Calcium which has an atomic number of 20 (or protons number, or z). The mass number is given by the sum of protons and neutrons. If the number of protons in this case is 20 and the number of neutrons is also 20, the mass number A = 40.
Answer:
B.) Oxygen is usually -2
Explanation:
Hydrogen is usually +1.
A pure group 1 element is not always +1.
A monoatomic ion can be a range of numbers. However, it must be a charge other than 0.
First, we have to see how K2O behaves when it is dissolved in water:
K2O + H20 = 2 KOH
According to reaction K2O has base properties, so it forms a hydroxide in water.
For the reaction next relation follows:
c(KOH) : c(K2O) = 1 : 2
So,
c(KOH)= 2 x c(K2O)= 2 x 0.005 = 0.01 M = c(OH⁻)
Now we can calculate pH:
pOH= -log c(OH⁻) = -log 0.01 = 2
pH= 14-2 = 12
Explanation:
1g = 1000mg
154000mg = 154g
No of days she can drink = 154÷ 11 = 14days
