Answer: The distance of the earth from the sun is 
Explanation:
Speed of light = 
Time taken to travel from sun to earth = 8.30 mins = 
(1min=60 s)
As we know ; Speed is defined as the distance travelled per unit time.
Hence distance between sun and earth =
Thus the distance of the earth from the sun is
Answer:
The first five elements of the periodic table are:- hydrogen, helium, lithium, beryllium, boron
Explanation:
atomic number- it is represented by the letter Z. It is basically the total number of protons present in each atom's nucleus of that element.
atomic mass- is the mass of a single atom present in the element.
electrons and protons- they are negatively and positively charged particles found in the nucleus of the atom respectively.
neutrons- they have no or zero charge and weigh more than protons.
element | atomic number | atomic mass | electrons | protons | neutrons
hydrogen (H)- 1 | 1.008 | 1 | 1 | 0
helium (He) - 2 | 4.0026 | 2 | 2 | 2
Lithium (Li) - 3 | 6.94 | 3 | 3 | 4
beryllium (Be) - 4 | 9.0122 | 4 | 4 | 5
Boron ( B) - 5 | 10.81 | 5 | 5 | 6
Answer:
the initial temperature of the iron sample is Ti = 90,36 °C
Explanation:
Assuming the calorimeter has no heat loss to the surroundings:
Q w + Q iron = 0
Also when the T stops changing means an equilibrium has been reached and therefore, in that moment, the temperature of the water is the same that the iron ( final temperature of water= final temperature of iron = T )
Assuming Q= m*c*( T- Tir)
mc*cc*(T-Tc)+mir*cir*(T - Tir) = 0
Tir = 20.3 °C + 300 g * 4.186 J/g°C * (20.3 C - 19 °C) / ( 51.9 g * 0.449 J/g°C )
Tir = 90.36 °C
Note :
- The specific heat capacity of water is assumed 1 cal/g°C = 4.186 J/g°C
- We assume no reaction between iron and water
Hrxn = Q reaction / mol of reaction
mol of reaction = M * V = 10 * 1 = 10 mmol = 0.01 mol
Q water = m * C * (Tf - Ti)
= (10 + 10) (4.184) (26-20) = 502.08 J
Q reaction = - Q water = -502.08 J
Hrxn = -502.08 / (0.01) = - 50208 J = - 50.21 kJ/mol
Answer:
We will expect 4 moles of MgO to be formed (option b).
Explanation:
Step 1: The balanced equation
2Mg + O2 → 2MgO
Step 2: Data given
Number of moles of Magnesium = 4 moles
Oxygen = in excess → this means Magnesium is the limiting reactant
Magnesium will completely be consumed ( 4 moles). There will remain 0 moles.
For 2 moles of magnesium consumed, we need 1 mole of oxygen to produce 2 moles of MgO.
For 4 moles of magnesium, we need 4/2 = 2 moles of oxygen.
For 4 moles of magnesium, we will produce 4/1 = 4 moles of MgO
We will expect 4 moles of MgO to be formed (option b).
