There are 34 protons , 45 neutrons and 36 electrons, in that order are present in the anion formed by one atom of 79Se .
Calculation
The number of electron / protons ( present in the nucleus ) of the atom is equal to atomic number .
The sum of number of electron / protons ( present in the nucleus ) and neutrons ( present in the nucleus ) of the atom is called atomic mass.
The atomic number of Se = 34
The Mass number or atomic mass of Se = 79
The anion of Se =
It means two electron loss by Se and form .
So , the difference between number of electrons and protons = 2
Hence , number of electron and proton in anion is 34 ( two less than number of protons ) and 36
To learn more about neutrons please click here .
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Answer:
answer is A. Alkaline metal lose two electrons not gain
Answer:
Below
Nitric acid
Lead
Sodium nitrate
Explanation:
The activity series is an arrangement of metals in order of decreasing reactivity. Metals that are higher up in the series displace metals that are lower in the series from dilute solutions. Hence, when the ion of a metal that is lower in the series reacts with a metal that is higher up in the series, the latter is oxidized.
Dilute acids dissolve metals above hydrogen in the activity series such as as zinc and lead. Platinum is much lower than sodium in the activity series hence platinum does not react with sodium nitrate.
Answer:
It is a right triangle
Explanation:
We are given the directions in which a bird flew to make a triangle.
We are required to determine whether the triangle is right angle.
What is a right triangle?
- It is a triangle that has a right angle between the shorter sides or legs
- The triangle also obeys the Pythagoras theorem, such that the square of the two legs is equal to the square of the hypotenuse.
- Such that if the two legs are, a and b while c is the hypotenuse.
Then, a² + b² = c²
In this case;
Taking the legs as a= 21 yards and b = 72 yards and the hypotenuse, c = 75 yards.
Then we can determine whether it is a right triangle;
a² = 21² = 441
b²= 72² = 5184
c² = 75² = 5625
a² + b² = 5625
Therefore; a² + b² = c²
Hence, the triangle is right triangle.
Density is calculated as mass divided by volume. We are given the mass of 15.0 grams, so we need to find the volume. For a cube, volume is calculated as (length of side)^3, so in this case, we have the length of a side as 44.5 mm, which is equivalent to 4.45 cm.
Volume = (4.45 cm)^3 = 88.1 cm^3
Then we divide mass by the volume:
Density = (15.0 grams) / (88.1 cm^3) = 0.170 g/cm^3
So the correct answer is A.