Positron emission = emission of a positron and a neutrino when a
proton is convert into a neutron. The total number of particles in the
nucleus doesn't change, -1 proton +1 neutron
It's a spontaneous reaction for some nucleus.
eg:
Positron = e+
Neutrino=ve
O-15 --> N-15 + e+ +ve
Electron
capture= A nucleus absorb an electron while a proton is convert in a
neutron and emit a neutrino. The total number of particles in the
nucleus doesn't change, -1 proton +1 neutron
eg:
Al-26 +e- --> Mg-26 + ve
Electron
capture and positron emission are two mechanisms to explain the decay
of some unstable isotopes. Electron capture is usually observed when the
energy difference between the initial and final state is low. Mainly
because of the larger amount of kinetic energy need for the expulsion
two particles with the positron emission mechanism.
A phylogenetic tree may be built using morphological (body shape), biochemical, behavioral, or molecular features of species or other groups. In building a tree, we organize species into nested groups based on shared derived traits (traits different from those of the group's ancestor).
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<h3>
What are Isomers ?</h3>
Isomers are compounds which have same empirical formula , same number of atoms are present but they have difference in arrangement if the atoms.
It is given that
There are four cis, trans isomers for 2-isopropyl-5-methylcyclohexanol
the cis, trans designations of the substituents are made relative to the oh group
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Answer: a) The substance is a silvery white, lustrous metal :physical property.
b) It melts at 649°C and boils at 1105°C : physical property.
c) Its density at 20°C is
: physical property.
d) The substance burns in air, producing an intense white light : chemical property
Explanation:
Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.
Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.
a) The substance is a silvery white, lustrous metal is a physical property
b) It melts at 649°C and boils at 1105°C is a physical property.
c) Its density at 20°C is
is a physical property.
d) The substance burns in air, producing an intense white light is a chemical property