Answer: b. One atom transferring electrons to another atom
Explanation: An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element and the element which accepts the electrons is known as electronegative element. This bond is formed between a metal and an non-metal.
Covalent bonds are formed by sharing of electrons between non metals
For example, In calcium iodide the one electron from calcium metal gets transferred to iodine atom and thus form an ionic bond to give 
Electronic configuration of calcium:
![[Ca]=1s^22s^22p^63s^23p^64s^2](https://tex.z-dn.net/?f=%5BCa%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E64s%5E2)
Calcium atom will lose two electron to gain noble gas configuration and form calcium cation with +2 charge.
![[Ca^{2+}]=1s^22s^22p^63s^23p^6](https://tex.z-dn.net/?f=%5BCa%5E%7B2%2B%7D%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E6)
Electronic configuration of iodine:
![[I]=1s^22s^22p^63s^23p^64s^23d^{10}4p^5](https://tex.z-dn.net/?f=%5BI%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E64s%5E23d%5E%7B10%7D4p%5E5)
Iodine atom will gain one electron to gain noble gas configuration and form iodide ion with -1 charge.
![[I^-]=1s^22s^22p^63s^23p^64s^23d^{10}4p^6](https://tex.z-dn.net/?f=%5BI%5E-%5D%3D1s%5E22s%5E22p%5E63s%5E23p%5E64s%5E23d%5E%7B10%7D4p%5E6)
Answer : The mathematical equation used when solving calorimetry problems is:

Explanation :
Calorimetry : It is determining the changes in the energy of a system by measuring the heat transferred with surroundings.
Formula used :

where,
c = specific heat capacity of calorimeter
m = mass of a substance
q = heat required
= change in temperature of substance
Answer:
The answer to your question is B. metallic
Explanation:
Covalent bonding is a bond between two nonmetals and the difference in electronegativity is between 0 and 1.7. Sodium could not have this kind of bond because is a metal.
Ionic bonding is a bond between a metal and a nonmetal and the difference of electronegativity is higher than 1.7. Sodium can have this kind of bond it is necessary one nonmetal.
Metallic, sodium has a metallic bond because this bond is characteristic of metals.
If its a unicellular orgnism, it has only one cell . no?
so i guess the answer has to be 1
Wavelength is 6.976 x 10^ -35 m
Explanation:
In this, we can use De Broglie’s equation. This equation is the relationship between De Broglie’s wavelength, velocity and the mass of a moving object. In this equation, we are using plank's constant which is 6.626 x 10^-34 m^2 kg/s.
We know that one mile per hour is equivalent to 0.447 M/S.
And One gram is equivalent to 10^-3 kg.
De Broglie’s wavelength = λ ( wave length) = Plank’s constant/ Mass x velocity
λ ( wave length) = 6.626 x 10^ -34/ (425 x10^-3) x ( 50 x 0.447)
= 6.626 x 10^ -34/ 0. 425 x 22.35
= 6.626 x 10^ -34/ 9.498
= 6.976 x10^ -35 m
So, the wavelength of the football will be 6.976 x 10^ -35 m