\(1.21 × 10^5\)
\(100\) g of haemoglobin contains \(0.34\) g of iron (As per the question)
\(3.3\) g of haemoglobin contains
\(\frac{0.34}{100}×3.3\) g of iron moles of \(Fe\)
=\(\frac{0.34×3.3}{100×56} = \frac{N}{N_A}\)
\(N =\frac{ 0.34 \times 3.3 \times 6.022 \times 10^{23}}{100 \times 56}\)
= \(1.21 \times 10^{20}\)
At STP \(x\) g of a metal hydrogen carbonate (MHCO$_3$) (molar mass \(84 \, {g/mol}\)) on heating gives CO$_2$, which can completely react with \(0.02 \, {moles}\) of MOH (molar mass \(40 \, {g/mol}\)) to give MHCO$_3$. The value of \(x\) is:
The heat generated in 1 minute between points A and B in the given circuit, when a battery of 9 V with internal resistance of 1 \(\Omega\) is connected across these points is ______ J. 
Such a group of atoms is called a molecule. Obviously, there must be some force that holds these constituent atoms together in the molecules. The attractive force which holds various constituents (atoms, ions, etc.) together in different chemical species is called a chemical bond.
There are 4 types of chemical bonds which are formed by atoms or molecules to yield compounds.