Step 1: Definition of National Political Party
According to the Election Commission of India (ECI), a political party is recognized as a national party if it fulfills certain criteria such as securing a minimum percentage of votes and recognition in at least four states.
Step 2: List of national political parties in India (as per recent classification)
1. Bharatiya Janata Party (BJP)
2. Indian National Congress (INC)
3. Communist Party of India (CPI)
4. Communist Party of India (Marxist) (CPI-M)
5. Bahujan Samaj Party (BSP)
6. Nationalist Congress Party (NCP)
7. All India Trinamool Congress (AITC)
Step 3: Conclusion
Therefore, there are a total of seven national political parties in India.
\[
\boxed{7 \ \text{National Parties}}
\]
Find the unknown frequency if 24 is the median of the following frequency distribution:
\[\begin{array}{|c|c|c|c|c|c|} \hline \text{Class-interval} & 0-10 & 10-20 & 20-30 & 30-40 & 40-50 \\ \hline \text{Frequency} & 5 & 25 & 25 & \text{$p$} & 7 \\ \hline \end{array}\]
Two concentric circles are of radii $8\ \text{cm}$ and $5\ \text{cm}$. Find the length of the chord of the larger circle which touches (is tangent to) the smaller circle.