The two effective drugs which act as life-saving drugs for cancer therapy and AIDS victims respectively are:
Cisplatin is particularly effective against testicular cancer. Taxol (paclitaxel) is a mitotic inhibitor used in cancer chemotherapy. AZT is used for helping AIDS victims.
Which of the following statements is/are correct?
Two or more atoms combine to give molecules.
The atoms of different elements are present in a compound in a fixed and definite ratio.
These two are correct by concepts of chemistry.
The prefix used for 10-18 is:
The prefix used for 10-18 is: atto-
The coefficient in 6.65 × 104 is:
Here 6.65 is the coefficient and 104 is the exponent.
One atomic mass unit (amu) is closest to:
One atomic mass unit is equal to 1.66×10−27kg. It is equal to 1/12th of the mass of an atom of carbon-12. It is abbreviated as amu.
The number of base SI units is:
Base is system means fundamental physical quantities and there are 9 fundamental physical quantities but only 7 have units so number of base SI units is 7.
The SI unit of time is:
The SI unit of time, the second, symbols, is easy enough to define, but time itself can only be defined in reference to other quantities.
The ‘Candela’ is the unit of:
Luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela, an SI base unit.
The number of significant figures in 3256 is:
3256, This number has four non zero numbers. That's why it has four significant figures.
The SI unit of electric current is:
The SI unit for measuring an electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. Electric current is measured using a device called an ammeter.
A number of significant figures in 0.001520 is:
The rules of determining the number of significant figures:
If the true value for a result is 2.00 g and a student takes 2 measurements and reports the results as 1.95 g and 1.93 g, then we can conclude that:
Precision indicates how closely repeated measurements match each other. Since both the values are close to each other, they are precise and since their is a difference between the mean value and true value, they are not accurate.
The unit of amount of substance is:
Out of the numbers: 6.26, 5.8, 0.00267, 0.03, the one with the least significant figures is:
6.26 & 0.00267 contains 3 significant figures while 5.8 has two significant figures and 0.03 contains least that is 1.
If the true value for a result is 3.00 m and a student records two readings as 3.01 m and 2.99 m, then we can conclude that:
Precision indicates how closely repeated measurements match each other.
Accuracy indicates how closely a measurement matches the correct or expected value.
The number of significant figures in 3.1205 are:
The answer is 5 because all non zero digits and zero between the non zero digits are significant.
The scientific notation for 0.00016 is:
Here, the decimal has to be moved four places to the right side and hence -4 is the exponent in the scientific notation.
Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2 weighs 10 g and 0.05 mole of X3Y2 weighs 9 g, the atomic weights of X and Y are:
Let atomic weight of element X is x and that of element Y is y.
If we add the numbers 6.68 and 0.8, the result will be:
During addition, the result cannot have more digits to the right of the decimal point than either of the original numbers. Since there is only 1 digit after the decimal point in 0.8 so the result 7.48 round off we will get 7.5.
Molecular mass of glucose molecule (C6H12O6) is:
Molecular mass: The sum of the atomic masses of all the atoms in a molecule of a substance is called the molecular mass of the molecule.
Generally we use relative atomic masses of atoms for calculating the molecular mass of 1 mole of any molecular or ionic substances.
Molecular formula of glucose is C6H12O6
Atomic mass of H = 1
Atomic mass of C = 12
Atomic mass of O = 16
Molecular mass of C6H12O6 = 12 (Atomic mass of Hydrogen) + 6(Atomic mass of carbon) + 6(Atomic mass of oxygen)
= 12 × 1 + 6 × 12 + 6 × 16
= 12 + 72 + 96 = 180 u.