The simple trick which one can consider in such problem where it is asked for positron emission is :
<span>When the atomic number goes DOWN by one and mass number remains unchanged, then a positron is emitted.
</span>
<span>a. </span>

<span>
Here the atomic number decreases by one.
Similarly, options b and d are eliminated.
Option c is also not the answer.
For c, Count the atomic number on left side and compare it with right side. You will see it is 9 on left and 8 on right. Atomic no. did go down by 1. But the atomic mass is changed as well.
</span>
A cold-blooded animal. Cold-blooded animals can't generate heat themselves so they have to use external sources to keep them warm.
Answer:
0.025 g C6H12O6
Explanation:
ppm = (g solute/ g solution)* 10^6
g solute= (ppm * g solution)/ 10^6
g solute = (250 ppm * 100 g)/10^6
g solute=0.025 g C6H12O6
Explanation:
Given
The enthalpy of formation of RbF (s) is –557.7kJ/mol
The standard enthalpy of formation of RbF (aq, 1 m) is –583.8 kJ/mol
The enthalpy of solution of RbF = Enthalpy of RbF (aq) - Enthalpy of formation of RbF (s)
= -583.8 - (-557.7) kJ/mol
= -26.1 kJ/mol
The enthalpy is negative which means that the temperature will rise when RbF is dissolved.
Answer:
357.475
Explanation:
First you need periodic table and you have to look for mass
Fe = 3 x 55.845 = 167.535
P = 2 x 30.97 = 61.94
o = 4 x 2 so 8 oxygen = 8 x 16 = 128
add all and you get 357.475