Answer:
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Explanation:
double blind test. the control group receives a placebo. Why is a placebo used in a double-blind test? so that the effects on people in two different groups can be compared.
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Answer : When we consider the atmospheric pressure as 1 atm then according to the ideal gas equation we can find out the molar mass of any unknown by this formula ;
PV=nRT
so if the pressure increases than 1 atm then we can see from the above equation that it will result in greater value for the number of moles (n) in the above equation.
While n = m/M where m is mass of the unknown in g and M is molecular mass.
So, if pressure is higher then it will result in molar mass of unknown which is much smaller.
Answer:
The fraction of water body necessary to keep the temperature constant is 0,0051.
Explanation:
Heat:
Q= heat (unknown)
m= mass (unknown)
Ce= especific heat (1 cal/g*°C)
ΔT= variation of temperature (2.75 °C)
Latent heat:
ΔE= latent heat
m= mass (unknown)
∝= mass fraction (unknown)
ΔHvap= enthalpy of vaporization (539.4 cal/g)
Since Q and E are equal, we can match both equations:
Mass fraction is:
∝=0,0051
Answer:
D = A bond resulting from the transfer of one or more electrons.
Explanation:
Ionic bond:
It is the bond which is formed by the transfer of electron from one atom to the atom of another element.
Explanation:
Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.
For example:
Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion.
while by sharing of electrons covalent bond is formed.
Covalent bond:
It is formed by the sharing of electron pair between bonded atoms.
The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.
For example:
In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial negative.
