Is BCom a better choice for a science student?

A science candidate can join in B. Com. You may get a seat in the college also. There may not be any problem for getting a seat also. You can do CA, ICWA, ICS and MBA also after passing your B.Com. There should not be any problem.
Initially, you may feel a little difficulty in understanding the subjects. You have to spend more time learning the subject initially. Everything depends on how seriously you take the education and put good efforts to get a good percentage of marks.
You can even study B.Sc also if not an Engineering degree. After completing your B.Sc also if you want to take up CA also you can take up there will not be any problem.
So based on your interest you have to select the subject.

This confusing situation is very common in the life of the students when they have to decide their career line. The pressure of the parents is at one side and the own aspirations are at the other side.

The first and foremost thing is to identify ones interest and liking. If you have a liking for something then only there are chances to progress in that field. Doing something under force and compulsion will be a half hearted job leading to failure and disappointment.

You must introspect and find out your interest. Is it History or Geography? Is it Mathematics or Humanities? It is Engineering or Medical? Is it Science or Commerce?

The answer to these questions is very important and vital for deciding a career line.

Now coming to your query it is very clear that you are not having interest in engineering or computers. Science is not fascinating to you. You are talking about commerce and thinking to pursue it in your graduation. If you have sincere liking for that then the efforts should start simultaneously. If yes, go for it with full throttle and show to your parents that you can achieve in commerce much more than what they were expecting you to achieve in science. Take this challenge and believe me the world is for those who take challenges.

You can get admission in B.Com. directly based on your performance in 10+2 or by giving an entrance exam. There are so many good institution for B.Com. and after that many career lines will be opening for you in the business, industrial and commercial arena. If you can work hard doing CA is not a difficult proposition which is sure shot to a good career. After B.Com. one has ample opportunity to appear in competitive exams leading to good positions in the Govt department. One can also apply in many business houses and financial institutions. One can go for M.Com. to increase ones academic qualification for pursuit of better jobs.

So, every area has scope may be some areas are having better job prospects today but it changes with time as the business environment today is very dynamic. What I want to emphasise is when you have to do a lot of labour and hard work for making your career why not to do it in your area of interest.

So fix up your mind and do all out efforts to show excellence in that interest area. Today the time is for scorers. The mediocre will roam here and there and never settle in their life. So, instead of repenting later in the life it is better to work hard today.

A student of Science stream (in X+II) can change the stream and shift to Commerce stream or Humanities stream. But why do you want to change the stream, especially when you don't have any idea about the subjects which are being taught in Commerce? What is the purpose? Have you seriously thought the issue and then taken the decision? Have you discussed this with your elders and the teachers?

There are many issues involved. Please don't take any hasty decision. Please think over. If you are facing difficulties in a particular subject, then try to tackle the problem by taking tuition or by any other method ()consulting guide-books, etc.). Changing stream is possible but require introspection and proper guidance from knowledgeable seniors and parents.

A student who has studied in PCMC in +2 can go for B.Com.
A person I know had done so and he passed CA and is now an established Chartered Accountant. The initial transition period of a few weeks may be a bit confusing as the science student had not learned the basics of accountancy, book keeping etc. A support from a commerce student and an attitude to learn can remedy that. One can also undergo a tuition class for a month or so during the pre-admission vacation if one desires so.

B.Com has all the prospects of getting a job where eligibility is only graduation. Compared to other streams, B.Com has actually more general opportunities and also specialised opportunities like CA etc.

Unlike science streams B.Com students get more time at home to study and review as they do not have lab classes practicals, records etc. A person with regular study habits with sincerity and application mind can become much successful in B.Com.

You should proceed in your study - area which fascinate you enormously be it science or otherwise and without the real passion, you cannot be an excellent performer.
With the rapid advancements of jobs in all the sectors such as CA, Cost - accountant, ICWA, Company - secretary and Engineering, one can do well provided one is having inherent passion for a particular area.
A science graduate can even for specialisation in commerce area but this could be a time consuming process in learning the basics and hence a switch at the intermediate stage would be quite favourable to understand the fundamental of subjects if you are really interested for commerce.

Most of the parents want their children to study Engineering. Engineering becomes the default choice almost all the youngsters across India. Parents can't be blamed for the buzz towards Engineering. Engineering created a lot of jobs in India for the last 2 decades and all parents want their children to be in a better position in the future. Buzz towards engineering is fading nowadays and students are considering taking up other degrees as well.

Let me answer some of your questions,

Is it ok for a science student doing BCom?
Yes absolutely, there is nothing wrong in choosing B.Com in college as a science student in school. As you mentioned, the basics of commerce will be covered in College first year and you don't have to worry about it. Secondly, peer pressure is the main problem that we will face after choosing up the degree. You should be strong with your decision and be confident with that.

Challenges in college:
It is very unlikely that you will face any challenge in college. Commerce is not that hard for a science student to understand also basics will be mostly covered in the first year so it will be easy for you to understand all the concepts.

Are there entrance exams for joining BCom?
It depends upon the college and most of the colleges don't have the entrance exam for commerce degree. You don't have to worry about any entrance exam. You can focus on the studies and prepare for CA which has very scope in India.

All the best for your future!

This is usual and common situation in most of students while choosing career path. There are lot of aspects which bring into such situation but first of think, What exactly bought to this situation. Why are you not willing to continue in science sector? Is it right choice to choose B.com than Science Sector?
Why I am asking those question is it will help you only. As you mentioned that your parents are willing to go for Engineering. They may be insisting it by seeing few examples nearby or few references who are engineers and have better career. Its you who can give them assurance or convince about not going to Engineering but you have to have better career option before it.
You mentioned that you are willing to chose B.Com and want to CA but have you ever thought what is requirement or selective subjects needed for same? If not, start gathering information and understand it. You need to understand each and every aspect required for CA preparations. Once you able to judge yourself and made sure that you can achieve it or can go for it then you can present all those points to your parents and easily convince them for choosing your career.
However Science is best option as it has wider range of career paths than Commerce and Arts but you need to take more efforts. It doesnt mean that Commerce and Arts dont need any efforts.
Science sector gives you options like Engineering, Bsc, BCS and specialization in it also has wide range of options. If you go for Commerce then it is good field for preparing for Government sector fields along with CA too. Now a days we can see lot of students preparing for MPSC, UPSC and other competitive exams and there are lot of brighter opportunities in it too.
So finally I would like to suggest you that considering all wide range of career paths in fields you chose which would be better and gather all related information which can make you comfortable to go for it. You can take your parents help to understand so that they can change their mind too and give go ahead for better path.